Grant-free uplink transmission in unlicensed spectrum

ABSTRACT

Methods and devices for grant-free uplink transmission in unlicensed spectrum are provided. A base station (BS) transmits grant-free resource configuration information to one or more electronic devices (EDs). The grant-free resource configuration information is used to configure the ED for GF uplink transmission in unlicensed spectrum. The GF resource configuration information includes GF ED group-specific resource configuration information indicating GF ED group-specific time-frequency (T/F) resources of the unlicensed spectrum for GF uplink transmission. The ED(s) transmit grant-free uplink transmissions over the unlicensed spectrum in accordance with the GF resource configuration information.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/031,481, filed on Sep. 24, 2020 (Now U.S. Pat. No. 11,503,622 issuedon Nov. 15, 2022) and entitled “Grant-Free Uplink Transmission inUnlicensed Spectrum,” which is a continuation of U.S. patent applicationSer. No. 16/518,641, filed on Jul. 22, 2019 (Now U.S. Pat. No.10,791,569 issued on Sep. 29, 2020) and entitled “Grant-Free UplinkTransmission in Unlicensed Spectrum,” which is a continuation of U.S.patent application Ser. No. 15/694,558, filed on Sep. 1, 2017 (Now U.S.Pat. No. 10,362,593 issued on Jul. 23, 2019) and entitled “Grant-FreeUplink Transmission in Unlicensed Spectrum,” which applications arehereby incorporated herein by reference as if reproduced in itsentirety.

TECHNICAL FIELD

The present disclosure relates generally to wireless communications, andin particular embodiments, to grant-free uplink transmissions inunlicensed spectrum.

BACKGROUND

In wireless communication systems, an electronic device (ED), such as auser equipment (UE), wirelessly communicates with a Transmission andReceive Point (TRP), termed “base station”, to send data to the EDand/or receive data from the ED. A wireless communication from an ED toa base station is referred to as an uplink communication. A wirelesscommunication from a base station to an ED is referred to as a downlinkcommunication.

Resources are required to perform uplink and downlink communications.For example, an ED may wirelessly transmit data to a base station in anuplink transmission at a particular frequency and during a particulartime slot. The frequency and time slot used is an example of a physicalcommunication resource.

In an LTE grant-based transmission, the required transmission controlparameters are typically communicated via a Physical Uplink ControlChannel (PUCCH) and/or Physical Downlink Control Channel (PDCCH). Thebase station is aware of the identity of the ED sending the uplinktransmission using the granted uplink resources, because the basestation specifically granted those uplink resources to that ED. In agrant-free transmission, different EDs may send uplink transmissionsusing uplink resources shared by the EDs, without specificallyrequesting use of the resources and without specifically being grantedthe resources by the base station. One advantage of grant-freetransmission is low latency resulting from not having to request andreceive a grant for an allocated time slot from the base station.Furthermore, in a grant-free transmission, the scheduling overhead maybe reduced. However, the base station does not have information whichED, if any, is sending a grant-free uplink transmission at a particularmoment of time, which may require blind detection of grant-freetransmissions received at the base station. In other words, the basestation is required to determine which ED is transmitting. Therefore,the BS can use the combination of uplink reference symbols (RS) andoccupied time-frequency resources to identify a grant-free ED as well asthe transport block being received from that grant-free ED.

Some modes of communication may enable communications with an ED over anunlicensed spectrum band, or over different spectrum bands (e.g., anunlicensed spectrum band and/or a licensed spectrum band) of a wirelessnetwork. Given the scarcity and expense of bandwidth in the licensedspectrum, exploiting the vast and free-of-charge unlicensed spectrum tooffload at least some communication traffic is an approach that hasgarnered interest from mobile broadband (MBB) network operators. Forexample, in some cases uplink transmissions may be transmitted over anunlicensed spectrum band. Accordingly, efficient and fair mechanisms forgrant-free uplink transmissions in the unlicensed spectrum may bedesirable.

SUMMARY

According to a first aspect, the present disclosure provides a methodfor an ED in a wireless communication network. The method includes an EDreceiving grant-free (GF) resource configuration information from a basestation. The GF resource configuration information is used to configurethe ED for GF uplink transmission in unlicensed spectrum. The GFresource configuration information includes GF ED group-specificresource configuration information indicating GF ED group-specifictime-frequency (T/F) resources of the unlicensed spectrum for GF uplinktransmission. The ED transmits grant-free uplink transmissions over theunlicensed spectrum in accordance with the GF resource configurationinformation.

In some embodiments of the first aspect, the GF resource configurationinformation further comprises a GF ED group-specific radio networktemporary identifier (GFG-RNTI) for the ED to receive GFG common DCImessages from the base station.

In some embodiments of the first aspect, the method further includesperforming a clear channel assessment (CCA) in the unlicensed spectrumin accordance with the GF resource configuration information, whereintransmitting a GF uplink transmission over the unlicensed spectrumcomprises starting the GF uplink transmission in accordance with the GFresource configuration information if the CCA is successful.

In some embodiments of the first aspect, the GF uplink transmission ofone ED or multiple ED of the group over the unlicensed spectrum isaligned to: a common GF transmission cycle; a downlink (DL) group commontime alignment signal; a DL burst containing a Control Resource Set(CORESET) that includes ED-specific and/or group common DCI triggers; ora combination of two or more of the above.

In some embodiments of the first aspect, the GF resource configurationinformation is received at least partially via at least one of: agroup-specific configuration message comprising the GF ED group-specificresource configuration information to configure the EDs in the group forGF uplink transmission in the unlicensed spectrum; and an ED-specificconfiguration message.

In some embodiments of the first aspect, the GF resource configurationinformation is received entirely via radio resource control (RRC)signaling.

In some embodiments of the first aspect, the GF resource configurationinformation is received in part via RRC signaling and in part viadownlink control information (DCI) that is part of an ED-specific or agroup common trigger.

In some embodiments of the first aspect, the GF resource configurationinformation further includes information indicating a reference starttime and a GF transmission cycle period. In such embodiments, the ED mayalign the ED's GF uplink transmission in the T/F resources to the commonGF transmission cycle defined by the common GF transmission cyclereference start time and the common GF transmission cycle period.

In some embodiments of the first aspect, the GF resource configurationinformation further includes information indicating a plurality ofpotential GF occasions within a GF transmission cycle at which the EDcould potentially start a GF uplink transmission.

In some embodiments of the first aspect, the reference start time is anabsolute start time expressed as the index of an alignment time unit(ATU).

In some embodiments of the first aspect, the reference start time is atime offset relative to any one of: radio resource control (RRC)signaling carrying at least part of the GF resource configurationinformation; and downlink control information (DCI) carrying at leastpart of the GF resource configuration information.

In some embodiments of the first aspect, the ED determines the referencestart time based on the GF transmission cycle period and a current timervalue of any one of: system frame number; subframe number; and slotnumber.

In some embodiments of the first aspect, the GF ED group-specificresource configuration information further includes an indication of oneor more occupational bandwidth-compliant (OCB-compliant) frequencyhopping patterns to be used by one or more EDs in the group forgrant-free uplink transmission within the T/F resources. For example,one or more of the OCB-compliant frequency hopping patterns may includea sequence of frequency interlaces within the T/F resources, a sequenceof unlicensed channels to occupy within the T/F resources, or somecombination of the two.

In some embodiments of the first aspect, the GF ED group-specificresource configuration information further comprises an indication of anED-specific field format for a grant-free group (GFG) common downlinkcontrol information (DCI) message.

In some embodiments of the first aspect, the GF ED group-specificresource configuration information further includes informationindicating a grant-free frame structure to be used by the group of EDsfor grant-free uplink transmission in the unlicensed spectrum. The EDmay then transmit a grant-free uplink transmission over the unlicensedspectrum in accordance with the grant-free frame structure indicated inthe GF ED group-specific resource configuration information.

In some embodiments of the first aspect, the ED also receives, over theunlicensed spectrum resources, a multi-cast grant-free group (GFG)common time-alignment signal for the group of EDs, and times the ED'sgroup-aligned GF transmission in the unlicensed spectrum resources basedon the GFG common time-alignment signal.

In some embodiments of the first aspect, the ED receives the multi-castGFG common time-alignment signal by searching for the multi-cast GFGcommon time-alignment signal in a common time-frequency search spaceaccording to a target GF cycle periodicity.

In some embodiments of the first aspect, the method further includes theED receiving a multi-cast group-specific grant-free group (GFG) feedbackmessage on T/F resources of the unlicensed spectrum.

In some embodiments of the first aspect, the ED receives the multi-castGFG feedback message after a last grant-free uplink burst from one ofthe EDs in the group ends and within a maximum channel occupancy time(MCOT).

In some embodiments of the first aspect, the ED receives the multi-castGFG feedback message as part of a GFG common time-alignment message, theGFG feedback message comprising, for each of one or more EDs in thegroup, an information field that includes Ack/Nack feedback related toone or more transport blocks transmitted by the ED within one or moremost recent grant-free uplink bursts preceding the GFG Ack/Nack feedbackmessage.

In some embodiments of the first aspect, the method further includes theED receiving, over the unlicensed spectrum resources, a downlink burstfrom the base station containing a control resource set (CORESET) thatincludes an ED-specific downlink control information (DCI) trigger forthe ED. The ED may then time the ED's group-aligned GF transmission inthe unlicensed spectrum resources based on the downlink burst.

In some embodiments of the first aspect, at least part of the GFresource configuration information may be received via the ED-specificdownlink DCI trigger for the ED.

According to another broad aspect, the present disclosure provides anelectronic device that includes a memory storage and one or moreprocessors in communication with the memory storage. The memory storageincludes instructions that the one or more processors execute toconfigure the ED for GF uplink transmission in unlicensed spectrum. Theconfiguration is done in accordance with GF resource configurationinformation received from a base station, which includes GF EDgroup-specific resource configuration information indicating GF EDgroup-specific time-frequency (T/F) resources of the unlicensed spectrumfor GF uplink transmission. The one or more processors also execute theinstructions to transmit a grant-free uplink transmission over theunlicensed spectrum in accordance with the GF resource configurationinformation.

In some embodiments of the second aspect, the one or more processorsexecute the instructions to perform a clear channel assessment (CCA) inthe unlicensed spectrum in accordance with the GF resource configurationinformation. The ED may then start the GF uplink transmission inaccordance with the GF resource configuration information if the CCA issuccessful.

In some embodiments of the second aspect, the one or more processorsexecute the instructions to start the GF uplink transmission inalignment with the GF uplink transmission of one or more EDs in the GFgroup.

In some embodiments of the second aspect, the GF uplink transmission ofone ED or multiple ED of the group over the unlicensed spectrum isaligned to: a common GF transmission cycle; a downlink (DL) group commontime alignment signal; a DL burst containing a Control Resource Set(CORESET) that includes ED-specific and/or group common DCI triggers; ora combination of two or more of the above.

In some embodiments of the second aspect, the GF resource configurationinformation is received either: entirely via radio resource control(RRC) signaling, or in part via RRC signaling and in part via downlinkcontrol information (DCI) that is part of an ED-specific or a groupcommon trigger.

In some embodiments of the second aspect, the GF resource configurationinformation further comprises information indicating a reference starttime and a GF transmission cycle period. In such embodiments, the one ormore processors execute the instructions to align the ED's GF uplinktransmission in the T/F resources to the common GF transmission cycledefined by the common GF transmission cycle reference start time and thecommon GF transmission cycle period.

In some embodiments of the second aspect, the GF resource configurationinformation further comprises information indicating a plurality ofpotential GF occasions within a GF transmission cycle at which the EDcould potentially start a GF uplink transmission.

In some embodiments of the second aspect, the GF ED group-specificresource configuration information further includes an indication of oneor more occupational bandwidth-compliant (OCB-compliant) frequencyhopping patterns to be used by one or more EDs in the group forgrant-free uplink transmission within the T/F resources.

In some embodiments of the second aspect, one or more of theOCB-compliant frequency hopping patterns may include a sequence offrequency interlaces within the T/F resources, a sequence of unlicensedchannels to occupy within the T/F resources, or some combination of thetwo.

In some embodiments of the second aspect, the one or more processorsexecute the instructions to receive, over the unlicensed spectrumresources, a multi-cast grant-free group (GFG) common time-alignmentsignal for the group of EDs, and time the ED's group-aligned GFtransmission in the unlicensed spectrum resources based on the GFGcommon time-alignment signal.

In some embodiments of the second aspect, the one or more processorsexecute the instructions to search for the multi-cast GFG commontime-alignment signal in a common time-frequency search space accordingto a target GF cycle periodicity.

In some embodiments of the second aspect, the one or more processorsexecute the instructions to receive a multi-cast group-specificgrant-free group (GFG) feedback message on T/F resources of theunlicensed spectrum either i) after a last grant-free uplink burst fromone of the EDs in the group ends and within a maximum channel occupancytime (MCOT), or ii) as part of a GFG common time-alignment message, theGFG feedback message comprising, for each of one or more EDs in thegroup, an information field that includes Ack/Nack feedback related toone or more transport blocks transmitted by the ED within one or moremost recent grant-free uplink bursts preceding the GFG Ack/Nack feedbackmessage.

In some embodiments of the second aspect, the one or more processorsexecute the instructions to receive, over the unlicensed spectrumresources, a downlink burst from the base station containing a controlresource set (CORESET) that includes an ED-specific downlink controlinformation (DCI) trigger for the ED, and time the ED's group-aligned GFtransmission in the unlicensed spectrum resources based on the downlinkburst.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will be described in greaterdetail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a communication system.

FIG. 2 is a timing diagram showing an example of a listen-before-talk(LBT) procedure in accordance with European regulatory requirements forframe based equipment (FBE).

FIG. 3A is a timing diagram showing a first example of a radio resourcecontrol (RRC) signaling to configure a common grant-free (GF)transmission cycle in accordance with an embodiment of the presentdisclosure.

FIG. 3B is a timing diagram showing a second example of a RRC signalingto configure a common GF transmission cycle in accordance with anembodiment of the present disclosure.

FIG. 4A is a timing diagram showing two examples of frame structures forgrant-free uplink transmission in an unlicensed spectrum sub-bandaccording to an embodiment of the present disclosure.

FIG. 4B is a timing diagram showing a further two examples of framestructures for grant-free uplink transmission in an unlicensed spectrumsub-band according to an embodiment of the present disclosure.

FIG. 5 is a table showing examples of reservation overhead associatedwith the four frame structures shown in FIGS. 4A and 4B for variousrelative lengths of OFDM symbol durations, short interframe space (shorttime gap) durations, and clear channel assessment (CCA) durations.

FIG. 6A is a timing diagram showing an example of unlicensed spectrumaccess procedures by first and second EDs configured to align theirtransmission starting times based on a common GF transmission cycle toaccess a first unlicensed spectrum sub-band for grant-free uplinktransmission using a first frame structure in accordance with anembodiment of the present disclosure.

FIG. 6B is a timing diagram showing an example of unlicensed spectrumaccess procedures by third and fourth EDs configured to align theirtransmission starting times based on a common GF transmission cycle toaccess a second unlicensed spectrum sub-band for grant-free uplinktransmission using the first frame structure in accordance with anembodiment of the present disclosure.

FIG. 7A is a timing diagram showing an example of unlicensed spectrumaccess procedures by first and second EDs configured to align theirtransmission starting times based on a common GF transmission cycle toaccess a first unlicensed spectrum sub-band for grant-free uplinktransmission using a second frame structure in accordance with anembodiment of the present disclosure.

FIG. 7B is a timing diagrams showing an example of unlicensed spectrumaccess procedures by third and fourth EDs configured to align theirtransmission starting times based on common GF transmission cycles toaccess a second unlicensed spectrum sub-band for grant-free uplinktransmission using the second frame structure in accordance with anembodiment of the present disclosure.

FIG. 8 is a block diagram of an example encoder for forming a grant-freegroup feedback message in accordance with an embodiment of the presentdisclosure.

FIG. 9 is a timing diagram showing an example of a first ED that isconfigured to perform a synchronous CCA based on a first common GFtransmission cycle to access a first unlicensed spectrum sub-band forgrant-free uplink transmission being granted an uplink transmissiongrant for a second unlicensed spectrum sub-band and subsequentlyperforming a CCA to access the second unlicensed spectrum sub-band forgrant-based uplink transmission in accordance with an embodiment of thepresent disclosure.

FIGS. 10A, 10B, 10C and 10D are four tables depicting priority classesand associated channel access parameters for different sub-bandsub-carrier spacings and cyclic prefix lengths in a 5 GHz unlicensedspectrum band in accordance with an embodiment of the presentdisclosure.

FIGS. 11A, 11B, 11C and 11D are four tables depicting priority classesand associated channel access parameters for different sub-bandsub-carrier spacings and cyclic prefix lengths in a 60 GHz unlicensedspectrum band in accordance with an embodiment of the presentdisclosure.

FIG. 12 is a timing diagram showing an example of unlicensed spectrumaccess procedures by first and second EDs configured to align theirtransmission starting times based on a common grant-free group alignmentmessage to access an unlicensed spectrum sub-band for grant-free uplinktransmission in accordance with an embodiment of the present disclosure.

FIG. 13 is a timing diagram showing an example of unlicensed spectrumaccess procedures by first and second EDs configured to align theirtransmission starting times based on a periodic common grant-free groupalignment message to access an unlicensed spectrum sub-band forgrant-free uplink transmission in accordance with an embodiment of thepresent disclosure.

FIG. 14A is a timing diagram showing an example of unlicensed spectrumaccess procedures by first and second EDs configured to align theirtransmission starting times based on a common grant-free group alignmentmessage to access a first unlicensed spectrum sub-band for grant-freeuplink transmission in accordance with an embodiment of the presentdisclosure.

FIG. 14B is a timing diagram showing an example of unlicensed spectrumaccess procedures by third and fourth EDs configured to align theirtransmission starting times based on a common grant-free group alignmentmessage to access a second unlicensed spectrum sub-band for grant-freeuplink transmission in accordance with an embodiment of the presentdisclosure.

FIG. 15 is a flow diagram of example operations in an ED in accordancewith an embodiment of the present disclosure.

FIG. 16 is a flow diagram of examples operations in a base station inaccordance with an embodiment of the present disclosure.

FIGS. 17A and 17B are block diagrams of an example ED and base station,respectively.

FIGS. 18A and 18B are block diagrams of an example transmit chain andreceive chain, respectively.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

For illustrative purposes, specific example embodiments will now beexplained in greater detail below in conjunction with the figures.

The embodiments set forth herein represent information sufficient topractice the claimed subject matter and illustrate ways of practicingsuch subject matter. Upon reading the following description in light ofthe accompanying figures, those of skill in the art will understand theconcepts of the claimed subject matter and will recognize applicationsof these concepts not particularly addressed herein. It should beunderstood that these concepts and applications fall within the scope ofthe disclosure and the accompanying claims.

Moreover, it will be appreciated that any module, component, or devicedisclosed herein that executes instructions may include or otherwisehave access to a non-transitory computer/processor readable storagemedium or media for storage of information, such as computer/processorreadable instructions, data structures, program modules, and/or otherdata. A non-exhaustive list of examples of non-transitorycomputer/processor readable storage media includes magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,optical disks such as compact disc read-only memory (CD-ROM), digitalvideo discs or digital versatile discs (i.e. DVDs), Blu-ray Disc™, orother optical storage, volatile and non-volatile, removable andnon-removable media implemented in any method or technology,random-access memory (RAM), read-only memory (ROM), electricallyerasable programmable read-only memory (EEPROM), flash memory or othermemory technology. Any such non-transitory computer/processor storagemedia may be part of a device or accessible or connectable thereto.Computer/processor readable/executable instructions to implement anapplication or module described herein may be stored or otherwise heldby such non-transitory computer/processor readable storage media.

Aspects of this disclosure provide a grant-free transmission mode foruplink transmissions in unlicensed spectrum in a wireless network. Inthis disclosure, grant-free transmissions refer to data transmissionsthat are performed without communicating grant-based signaling.

Turning now to the figures, some specific example embodiments will bedescribed.

Communication System

FIG. 1 illustrates an example communication system 100 in whichembodiments of the present disclosure could be implemented. In general,the communication system 100 enables multiple wireless or wired elementsto communicate data and other content. The purpose of the communicationsystem 100 may be to provide content (voice, data, video, text) viabroadcast, multicast, unicast, user device to user device, etc. Thecommunication system 100 may operate by sharing resources such asbandwidth.

In this example, the communication system 100 includes electronicdevices (ED) 110 a-110 c, radio access networks (RANs) 120 a-120 b, acore network 130, a public switched telephone network (PSTN) 140, theinternet 150, and other networks 160. Although certain numbers of thesecomponents or elements are shown in FIG. 1 , any reasonable number ofthese components or elements may be included in the communication system100.

The EDs 110 a-110 c are configured to operate, communicate, or both, inthe communication system 100. For example, the EDs 110 a-110 c areconfigured to transmit, receive, or both via wireless or wiredcommunication channels. Each ED 110 a-110 c represents any suitable enduser device for wireless operation and may include such devices (or maybe referred to) as a user equipment/device (UE), wirelesstransmit/receive unit (WTRU), mobile station, fixed or mobile subscriberunit, cellular telephone, station (STA), machine type communication(MTC) device, personal digital assistant (PDA), smartphone, laptop,computer, tablet, wireless sensor, or consumer electronics device.

In FIG. 1 , the RANs 120 a-120 b include base stations 170 a-170 b,respectively. Each base station 170 a-170 b is configured to wirelesslyinterface with one or more of the EDs 110 a-110 c to enable access toany other base station 170 a-170 b, the core network 130, the PSTN 140,the internet 150, and/or the other networks 160. For example, the basestations 170 a-170 b may include (or be) one or more of severalwell-known devices, such as a base transceiver station (BTS), a Node-B(NodeB), an evolved NodeB (eNodeB), a Home eNodeB, a gNodeB, atransmission and receive point (TRP), a site controller, an access point(AP), or a wireless router. Any ED 110 a-110 c may be alternatively oradditionally configured to interface, access, or communicate with anyother base station 170 a-110 b, the internet 150, the core network 130,the PSTN 140, the other networks 160, or any combination of thepreceding. The communication system 100 may include RANs, such as RAN120 b, wherein the corresponding base station 170 b accesses the corenetwork 130 via the internet 150, as shown.

The EDs 110 a-110 c and base stations 170 a-170 b are examples ofcommunication equipment that can be configured to implement some or allof the functionality and/or embodiments described herein. In theembodiment shown in FIG. 1 , the base station 170 a forms part of theRAN 120 a, which may include other base stations, base stationcontroller(s) (BSC), radio network controller(s) (RNC), relay nodes,elements, and/or devices. Any base station 170 a, 170 b may be a singleelement, as shown, or multiple elements, distributed in thecorresponding RAN, or otherwise. Also, the base station 170 b forms partof the RAN 120 b, which may include other base stations, elements,and/or devices. Each base station 170 a-170 b transmits and/or receiveswireless signals within a particular geographic region or area,sometimes referred to as a “cell” or “coverage area”. A cell may befurther divided into cell sectors, and a base station 170 a-170 b may,for example, employ multiple transceivers to provide service to multiplesectors. In some embodiments there may be established pico or femtocells where the radio access technology supports such. In someembodiments, multiple transceivers could be used for each cell, forexample using multiple-input multiple-output (MIMO) technology. Thenumber of RAN 120 a-120 b shown is exemplary only. Any number of RAN maybe contemplated when devising the communication system 100.

The base stations 170 a-170 b communicate with one or more of the EDs110 a-110 c over one or more air interfaces 190 using wirelesscommunication links e.g. radio frequency (RF), microwave, infrared (IR),etc.. The air interfaces 190 may utilize any suitable radio accesstechnology. For example, the communication system 100 may implement oneor more orthogonal or non-orthogonal channel access methods, such ascode division multiple access (CDMA), time division multiple access(TDMA), frequency division multiple access (FDMA), orthogonal FDMA(OFDMA), or single-carrier FDMA (SC-FDMA) in the air interfaces 190.

A base station 170 a-170 b may implement Universal MobileTelecommunication System (UMTS) Terrestrial Radio Access (UTRA) toestablish an air interface 190 using wideband CDMA (WCDMA). In doing so,the base station 170 a-170 b may implement protocols such as HSPA, HSPA+optionally including HSDPA, HSUPA or both. Alternatively, a base station170 a-170 b may establish an air interface 190 with Evolved UTMSTerrestrial Radio Access (E-UTRA) using LTE, LTE-A, and/or LTE-B. It iscontemplated that the communication system 100 may use multiple channelaccess functionality, including such schemes as described above. Otherradio technologies for implementing air interfaces include IEEE 802.11,802.15, 802.16, CDMA2000, CDMA2000 1×, CDMA2000 EV-DO, IS-2000, IS-95,IS-856, GSM, EDGE, and GERAN. Of course, other multiple access schemesand wireless protocols may be utilized.

The RANs 120 a-120 b are in communication with the core network 130 toprovide the EDs 110 a-110 c with various services such as voice, data,and other services. The RANs 120 a-120 b and/or the core network 130 maybe in direct or indirect communication with one or more other RANs (notshown), which may or may not be directly served by core network 130, andmay or may not employ the same radio access technology as RAN 120 a, RAN120 b or both. The core network 130 may also serve as a gateway accessbetween (i) the RANs 120 a-120 b or EDs 110 a-110 c or both, and (ii)other networks (such as the PSTN 140, the internet 150, and the othernetworks 160). In addition, some or all of the EDs 110 a-110 c mayinclude functionality for communicating with different wireless networksover different wireless links using different wireless technologiesand/or protocols. Instead of wireless communication (or in additionthereto), the EDs may communicate via wired communication channels to aservice provider or switch (not shown), and to the internet 150. PSTN140 may include circuit switched telephone networks for providing plainold telephone service (POTS). Internet 150 may include a network ofcomputers and subnets (intranets) or both, and incorporate protocols,such as IP, TCP, UDP. EDs 110 a-110 c may be multimode devices capableof operation according to multiple radio access technologies, andincorporate multiple transceivers necessary to support such.

Grant-Free Transmissions

The base stations 170 are configured to support wireless communicationwith EDs 110, which may each send grant-free uplink transmissions.Uplink transmissions from the EDs 110 are performed on a set oftime-frequency resources. A grant-free uplink transmission is an uplinktransmission that is sent using uplink resources without the basestations 170 dynamically allocating resources to request/grantmechanisms. By performing grant-free transmissions, total networkoverhead resources may be saved. Furthermore, time savings may beprovided by bypassing the request/grant procedure. An ED sending agrant-free uplink transmission, or configured to send a grant-freeuplink transmission, may be referred to as operating in grant-free mode.Grant-free uplink transmissions are sometimes called “grant-less”,“schedule free”, or “schedule-less” transmissions. Grant-free uplinktransmissions from different EDs may be transmitted using shareddesignated resource units, in which case the grant-free uplinktransmissions are contention-based transmissions. One or more basestations 170 may perform blind detection of the grant-free uplinktransmissions.

In a wireless network according to an embodiment, any ED can beconfigured for grant-based or grant-free transmissions depending on,e.g., the application and device types and requirements. Usually, agrant-free transmission may require resource (pre-) configuration at theED connection setup and have resource reconfiguration or an updateduring operation. In some embodiments, the grant-free resources can beconfigured for EDs by broadcast or multi-cast signaling in somescenarios. Two or more grant-free transmissions can share the sameconfigured resources. Furthermore, in some embodiments, a grant-basedtransmission can use dedicated resources or can share resources (fullyor partially) with grant-free resources in a time interval.

Any of the grant-free and grant-based transmissions can be used for anyapplication traffic or services type, depending on the associatedapplication requirements and quality of service (QoS). By way of anon-limiting example, grant-free transmission can be used for:ultra-reliable low latency communication (URLLC) traffic to satisfy thelow latency requirement; enhanced mobile broadband (eMBB) traffic withshort packets to save signaling overhead; and eMBB traffic todynamically take advantage of link adaptation and enhance resourceutilization and spectrum efficiency.

One ED or a group of EDs may have a group ID or Radio Network TemporaryID (RNTI; e.g., grant-free (GF)-RNTI or grant-based (GB) RNTI) to sharethe same parameter or resource configuration. The group ID can bepre-configured, or dynamically configured to each ED. The parameter orresource configuration to the ED(s) with the group ID can be done bysemi-static or dynamic signaling. In some embodiments, the group ID canbe used for, e.g., resource deactivation or activation for the EDs inthe group. By way of a non-limiting example, the resources beingactivated or deactivated can include frequency, time, and referencesignal (RS) associated with each ED in the group.

Grant-free transmission eliminates the latency and control overheadassociated with the scheduling request/grant procedure of grant-basedtransmission and can allow for more transmission repetitions to increasethe likelihood of successful detection or achieve a desired reliability.

Moreover, unlike contention-free schemes such as GB schemes, in acontention based grant-free scheme uplink resources are accessible toall grant-free EDs served by the same base station, i.e., controlledintra-cell contention/collisions are allowed, thus leading to anefficient utilization of resources and potentially increased systemcapacity.

For reasons such as the foregoing, uplink grant-free transmission hasbeen agreed to be supported in the 3GPP study item for the 5G New Radio(NR) air interface.

However, for EDs experiencing bad channel conditions and/or persistentharmful collisions, switching a transport block (TB) to contention-freegrant-based transmission is often desired to ensure successful decodingand/or to exploit link adaptation of uplink scheduling by the basestation compared to the pre-configured transport formats used ingrant-free transmission.

Grant-Free Resource Structure

To support grant-free transmissions, the associated resources configuredfor an ED or a group of EDs can include any or all of the following:

1) Frequency resources in a transmission time interval (TTI), e.g. asymbol, mini-slot or slot. In one example, a physical resource block(PRB) scheme is provided. The PRB scheme indicates physical startingfrequency resource block (RB) and size of the RB.

2) Time resources, including starting/ending position of one datatransmission time interval. For example, TTI can be one symbol,mini-slot, or slot.

3) Reference signal (RS) or RS configuration, where each ED can beconfigured with one or more reference signals (RSs) e.g. demodulationreference signals (DMRSs) depending on scenarios involved. For a groupof EDs, each ED may or may not have a different RS or have a differentset of RSs. Note that different RSs can be orthogonal or non-orthogonalto each other depending on an application, e.g., such as URLLCapplication or massive machine-type communication (mMTC) application.

4) ED/ED group specific hopping parameters, which may include one of thefollowing two parameters. One parameter may include a hopping patterncycle period. In one embodiment, an absolute reference duration (e.g.,20 TTI before repeating itself) is defined. During the absolutereference duration, the number of hopping steps (e.g., 10 times) to takebefore repeating the hopping pattern again can be determined based onperiodicity of time interval resource accessible for grant-freetransmissions (e.g., 2 TTI). In another embodiment, an absolute numberof hopping times can be defined, for example hopping 20 times beforerepeating itself. Other parameter(s) may include a hopping pattern indexor indices, where one ED may have one or more hopping pattern indices.

5) One or more hybrid automatic repeat request (HARQ) process IDs perED.

6) One or more MCSs per ED, where a grant-free ED can indicateexplicitly or implicitly which MCS to use for a transmission.

7) Number of grant-free transmission repetitions K, one or more K valuescan be configured for an ED, where which K value to use depends oncertain rule taking into account ED channel conditions, service types,etc.

8) Power control parameters, including power ramping step size (e.g.,for an ED).

9) Other parameters, including information associated with generalgrant-based data and control transmissions. Note that sometimes, asubset of grant-free resources can be referred to as “fixed” or“reserved” resources; whereas a subset of grant-based resources can bereferred to as “flexible” resources, which can be dynamically scheduledby a base station.

Hybrid Automatic Repeat Requests

As discussed above, the ED 110 may be configured to use a particular setof resources for grant-free transmission. A collision may occur when twoor more of the EDs 110 attempt to transmit data on a same set of uplinkresources. To mitigate possible collisions, the EDs 110 may useretransmissions. A retransmission, without grant, of an originalgrant-free uplink transmission is referred to herein as a “grant-freeretransmission”. Any discussion of a grant-free retransmission hereinshould be understood to refer to either a first or a subsequentretransmission. Herein, the term “retransmission” includes both simplerepetitions of the transmitted data, as well as retransmissions using anasynchronous hybrid automatic repeat request (HARQ), that is, acombination of high-rate forward error-correcting coding and physicallayer automatic repeat request (ARQ) error control.

In an embodiment, a number of automatic grant-free retransmissions maybe pre-configured, to improve reliability and eliminate latencyassociated with waiting for an acknowledgement (ACK) or a negativeacknowledgement (NACK) message. The retransmissions may be performed bythe ED 110 until at least one of the following conditions is met:

(1) An ACK message is received from the base station 170 indicating thatthe base station 170 has successfully received and decoded the TB. TheACK may be sent in a dedicated downlink acknowledgement channel, sent asindividual Downlink Control Information (DCI), sent in a data channel,sent as part of a group ACK/NACK, etc.

(2) The number of repetitions reaches K. In other words, if the ED 110has performed K retransmissions and an ACK is still not received fromthe base station 170, then the ED 110 gives up trying to send the datato the base station 170. In some embodiments, K is semi-staticallyconfigured by the base station 170, such that the base station 170 orthe network can adjust K over time.

(3) A grant is received from the base station 170 performing agrant-free to grant-based switch.

In an embodiment, the grant-free retransmission may be triggered byreceiving a negative acknowledgment (NACK) message, or failing toreceive an acknowledgment (ACK) message. In an alternative embodiment, Kgrant-free retransmissions are performed irrespective of the responsefrom the base station 170.

The resources over which the one or more grant-free retransmissions areperformed may be pre-configured, in which case the base stationdetermines the resources based on a priori information. Alternatively,the resources over which the grant-free initial transmission or one ormore retransmissions are performed may be determined e.g. according toan identifier in a pilot signal of the original grant-free uplinktransmission. This may allow the base station to predict, or otherwiseidentify, which uplink resources will carry the one or moreretransmissions upon detecting the identifier in the pilot symbol.

Grant-free transmission reduces latency and control overhead associatedwith grant-based procedures, and can allow for moreretransmissions/repetitions to increase reliability. However, due to thelack of uplink scheduling and grant signaling, grant-free EDs may haveto be pre-configured to use a fixed modulation and coding scheme (MCS)level at least for initial grant-free transmission. In one embodiment,grant-free EDs are configured to use the most reliable MCS level for agiven resource unit for grant-free uplink transmissions.

Link Adaptation for Grant-Free Transmissions

The use of link adaptation for grant-free transmissions andretransmissions potentially offers several benefits, such as:

Uplink transmissions may occupy fewer resources. For example, EDs withgood link quality may be able to use fewer resources by using higher MCSlevels.

Spectral efficiency may be increased, and thus the grant-free systemcapacity may similarly be increased.

Target reliability as characterized e.g. by target residual block errorrate (BLER), may be attained more efficiently.

The link adaptation for grant-free communications may be provided byusing a semi-static or dynamic signaling, e.g., periodic signaling witha configurable period. This mechanism may follow an approach similar tothat of grant-based uplink dynamic closed loop transmit power control toachieve a target performance metric, such as residual BLER. Otherperformance metrics that may serve as a target performance metricinclude, but are not limited to:

The percentage of decoding instances at the base station resulting inNACKs and/or the percentage of decoding failures, compared to a targetthreshold.

The percentage of decoding instances at the base station resulting inACKs, and/or the percentage of decoding successes, compared to a targetthreshold.

The SINR gap between the received combined SINR (combined over all HARQretransmissions of each TB) and the target SINR associated with thecurrent MCS level in use.

Decoding Log Likelihood Ratios (LLRs) calculated by the base stationwhen attempting to decode a TB after combining all of itsretransmissions and given the current MCS level in use.

A command for the ED to adjust MCS may be transmitted over a dedicateddownlink control channel, e.g. the Physical Downlink Control Channel(PDCCH) or combined with acknowledgement messages over a dedicateddownlink acknowledgement channel, e.g. combined with Hybrid AutomaticRepeat Request (HARQ) acknowledgements (ACKs/NACKs) transmitted over thePhysical HARQ Indicator Channel (PHICH) or other channels.

The grant-free link adaptation may also be initiated at the ED. In oneembodiment, an ED can measure downlink channel conditions, and deriveuplink channel conditions based on the measured downlink channelconditions. The ED may adapt various parameters of its uplinktransmissions based on the assumed uplink channel conditions. The ED maythen inform the base station of the adapted transmission parameters.Additionally or alternatively, based on the assumed uplink channelconditions, the ED may send to the base station an indication of atransmission adaptation.

Among the uplink transmission parameters that may be adapted are theMCS, packet size, the segmentation of packets, the repetition ofpackets, and numerology. The numerology may include the spacing ofsubcarriers in uplink transmissions and the length of the cyclic prefixused in uplink transmissions. Such adaptations may take into account thedownlink channel quality measurements, the ED's mobility, pilot signalcollisions, the QoS of the ED, including the latency requirement of theED.

The link adaptation for grant-free communications may also be providedby pre-configuring resource groups that with different MCS levels forgrant-free transmission with different link conditions. The resourcegroups can be of different numerologies to enable varying resourceconfigurations. A grant-free ED's long term geometry or path loss and/ortransport block packet size may be used to map to a particular one ofthe pre-configured resource groups.

Unlicensed Spectrum Access

As noted above, given the scarcity and expense of bandwidth in thelicensed spectrum, and the increasing demand for data transmissioncapacity, there is increasing interest in offloading at least somecommunication traffic, such as uplink communication traffic, to theunlicensed spectrum. For example, there has been significant interest inthe unlicensed 5 GHz spectrum in which many Wireless Local Area Networks(WLANs) operate. Accordingly, in order to operate in this spectrum,efficient and fair coexistence with WLANs along with compliance withregion-specific unlicensed spectrum regulations may be necessary.

Licensed-Assisted Access (LAA) and enhanced LAA (eLAA) of 3GPP Rel 13and Rel 14, respectively, aimed at porting the spectral-efficient MBBair interface (AI) to the vast and free-of-charge unlicensed spectrumthrough aggregating unlicensed component carriers (CCs) at theoperator's small cells with the assistance of the anchor licensedcarriers.

However, UL transmission in eLAA has been built around the GB schemeonly. To present a global unlicensed solution, regulatory requirementssuch as Listen-Before-Talk (LBT) have to be imposed on the medium accessdesign. As such, UL transmission in eLAA has been substantiallydisadvantaged in terms of latency and successful medium accessopportunities due to the multiple contention levels for:

ED to transmit the scheduling request (SR)

Base station to schedule the ED among other EDs

Base station to transmit the scheduled grant (especially forself-carrier scheduling)

ED to pursue the GB transmission.

Aspects of the present disclosure address the challenges of uplinktransmission in the unlicensed spectrum by enabling a GF transmissionscheme as part of the unified NR-U air interface. In addition, given theplentiful resources available in the unlicensed spectrum, someembodiments of the present disclosure could potentially provideUltra-Reliable Low-latency Communications (URLLC) applications in theunlicensed spectrum.

Before an ED can access unlicensed spectrum to transmit on an unlicensedspectrum sub-band, the ED performs a listen-before talk (LBT) operation(for example including initial clear channel assessment (ICCA) and anextended clear channel assessment (ECCA)) in order to check that thechannel is idle before transmitting. A sub-band of an unlicensedspectrum band may include a group of frequency resources that comprisesone or more unlicensed channels as defined by the IEEE 802.11 standardin the geographical region of operation, or one or more bandwidth parts(BWPs) as defined by 3GPP standard, for example.

In regions such as Europe and Japan, devices attempting to access theunlicensed spectrum have to comply with either a Load Based Equipment(LBE) LBT procedure or a Frame Based Equipment (FBE) LBT procedure.

In the LBE LBT procedure, a device attempting to access the unlicensedspectrum can start transmitting at an arbitrary time after a successfulCCA. The CCA mechanism employed in such LBE LBT procedures may be thesame CCA mechanism employed in WLAN, i.e. carrier sense multiple accesswith collision avoidance (CSMA/CA), or it may be based on anenergy-detection-based CCA. For example, an energy-detection-based CCAmay utilize a random backoff to determine the size of a contentionwindow and a respective maximum channel occupancy time(MCOT) thatdetermines the maximum amount of time that a device may transmit in theunlicensed spectrum once it has successfully contended for atransmission opportunity.

In FBE LBT procedures, a device attempting to access the unlicensedspectrum can start transmitting only at periodic instants after a shortsuccessful energy-detection-based CCA.

FIG. 2 is a timing diagram showing an example of an LBT procedure inaccordance with the European regulatory requirements set out in EuropeanTelecommunications Standards Institute (ETSI) EN 301 893 V1.7.1 fordevices accessing unlicensed spectrum as FBE. As depicted in FIG. 2 , adevice accessing unlicensed spectrum as FBE starts transmissions 200 ₁,200 ₂ over the unlicensed spectrum only at periodic instants 202 ₁, 202₂ after a short successful energy-detection-based CCA 204 ₁, 204 ₂indicating that a channel in the unlicensed spectrum is available. Theminimum time between such periodic instants 202 ₁, 202 ₂ is the fixedframe period 206, which encompasses the channel occupancy time 208 ofthe transmission and an idle period 210. Under the regulatoryrequirements set out in ETSI EN 301 893 V1.7.1, the channel occupancytime 208 may be between 1 and 10 milliseconds (ms) and the idle period210 must be at least 5% of the channel occupancy time 208, which meansthat the frame period 206 must be a minimum of 1.05 times the size ofthe channel occupancy time 208. In addition, under the regulatoryrequirements set out in ETSI EN 301 893 V1.7.1, devices employ anenergy-detection-based CCA in which a channel is determined to be busyif the total energy detected in the channel is greater than a CCAthreshold value that is upper bounded by a function of the transmitpower of the device. In particular, the upper bound of the CCA thresholdhas been regulated as follows:

$\begin{matrix}{{{CCA}{Threshold}} \geq {{{- 73}\frac{{dB}m}{MHz}} + \left( {23 - {\max{Tx}{EIRP}}} \right)}} & {\left\lbrack {{dB}m} \right\rbrack,}\end{matrix}$

where max Tx EIRP is a device's maximum transmit equivalentisotropically radiated power (EIRP). As a result, the higher the max Txpower and/or the antenna gain, the lower the CCA threshold that isallowed. As such, an unlicensed spectrum access opportunity may dependon the result of the transmit power control mechanism that is used forunlicensed spectrum transmission. Under the regulatory requirements setout in ETSI EN 301 893 V1.7.1, the CCA period must be at least 20microseconds (μs) long, with 25 μs being typical.

If individual EDs accessed the unlicensed spectrum individually withoutcoordination, it could create delay and potentially deteriorateperformance. For example, If EDs perform independent LBT procedures,they may either start transmitting uplink data or send a reservationsignal to ensure that other devices do not occupy an unlicensed channelbefore they are able to transmit. In both situations, if no coordinationexists between EDs in terms of aligning their CCAs, sending of thereservation signals or starting of their uplink transmissions, then thechannel may appear to be busy for other EDs, which can increase thelatency of uplink transmission for those other EDs.

For example, in the CSMA/CA LBT procedure utilized in WiFi/WLAN, eachdevice (e.g. WiFi access point (AP) or WiFi station (STA)) attempting toaccess the unlicensed spectrum independently generates a random backoffcounter or contention window (CW) that is used to determine the lengthof an ECCA that is performed after an ICCA that is performed during andistributed coordination function inter-frame space (DIFS). In theCSMA/CA LBT procedure, if a CCA is terminated due to a ‘busy’assessment, the backoff counter is frozen to maintain priority in thenext access attempt. WiFi/WLAN APs or STAs of the same basic serving set(BSS) can block each other, because there is no synchronous group accessin the CSMA/CA LBT procedure utilized in WiFi/WLAN. For a transmissionfrom a source device to a destination device in WiFi/WLAN, if the sourcedevice successfully receives one or multiple medium access controlprotocol data units (MPDUs), e.g., an aggregated MPDU (AMPDU), anacknowledgement (ACK) signal is sent using a reliable modulation andcoding scheme (MCS) from the destination device to the source deviceonly. A time out for the transmission is detected by the source deviceif the source device does not receive/decode an ACK within a time framedefined by the duration of a short inter-frame space (SIFS) plus theduration of the ACK after the source device finishes the transmission.

The 3rd Generation Partnership Project (3GPP) Release 13 Long TermEvolution (LTE) specification provides a framework for Licensed AssistedAccess (LAA) in unlicensed spectrum. The framework includes a Category 4(CAT4) LBT procedure (LBT with random backoff or ECCA) that each deviceattempting to access the unlicensed spectrum must comply with. Similarto the LBT mechanism in CSMA/CA for WIFI/WLAN, in the 3GPP Release 13CAT4 LBT mechanism each device independently generates a random backoffcounter or contention window (CW), and if a CCA is terminated due to a‘busy’ assessment, the backoff counter is frozen to maintain priority inthe next access attempt. However, synchronous group access ofneighboring small cell evolved Node Bs (eNBs) is supported in 3GPPRelease 13 via backhaul connections by setting a common starting timefor downlink (DL) transmissions from neighboring small cell eNBs. TheeNB that finishes a successful CCA before the preset subframe startingpoint has to defer its transmission to that point. However, the eNB thathas deferred its transmission cannot prevent WiFi or other LAA accessduring the defer time by transmitting a blank blocking/reservationsignal because this will likely cause the ongoing CCAs of in-group eNBsto fail.

GF UL Transmission in Unlicensed Spectrum

Methods and devices are provided that address the above challengesassociated with supporting grant-free uplink transmission in unlicensedspectrum. In some embodiments, EDs in the same group are configured toalign their transmission starting times following the success ofrespective LBT CCA procedures in order to access the unlicensed spectrumsimultaneously and share time-frequency resources of an unlicensedspectrum sub-band for grant-free uplink transmissions. Meanwhile, GF EDsin different groups can access the unlicensed spectrum in acontention-free manner.

As will described in further detail later on, the potential GFtransmissions of the group of EDs in unlicensed spectrum can be alignedto a common GF transmission cycle, a downlink (DL) group common timealignment signal, a DL burst containing a Control Resource Set (CORESET)that includes ED-specific and/or group common DCI triggers, or they maybe aligned using a combination of the above methods.

The configuration/re-configuration can be done through DL RRC signalingand/or group common physical downlink control channel (PDCCH). Theconfiguration can be carried in a grant free specific group commoncontrol PDCCH, a cyclic redundancy check (CRC) of which is scrambledwith a grant-free ED group RNTI (GFG-RNTI). The configuration can bealso carried in a general group common PDCCH, a CRC of which isscrambled by common control RNTI (CC-RNTI). Examples of RRC signalingare ED-specific, cell-specific, or group-specific RRC.

In some embodiments of the present disclosure, an ED that has beenconfigured for grant-free uplink transmission may not need to monitorED-specific downlink control information (DCI), unless functionality toswitch transmission of a TB from grant-free mode to GB mode is enabledor ED-specific DCI triggers are used to align the GF transmissions ofsome or all of the group EDs.

For embodiments of the present disclosure in which a group of EDs areconfigured to align their transmission starting times to a common GFtransmission cycle characterized by a GF transmission cycle referencetime and a GF transmission cycle period, EDs configured with the same GFtransmission cycle may be grouped into the same unlicensed spectrumsub-band. As mentioned earlier, an unlicensed spectrum sub-band mayinclude one or more BWPs or one or more unlicensed spectrum channels,e.g. with a bandwidth of 20/40/80/100/160 MHz.

A grant-fee ED configured to align to a common GF transmission cycle canthus access the unlicensed spectrum sub-band as an ETSI Frame BasedEquipment (FBE), i.e., if the grant-free ED needs to transmit, only ashort one-shot LBT (Category 2 (CAT2) LBT) is required immediatelybefore or immediately after the beginning of a new GF transmission cycleperiod without taking up part of a DL MCOT. Nonetheless, in someembodiments, a Category 4 (CAT 4—LBT with random back-off with variablesize of contention window or extended CCA) LBT procedure could be usedand configured via RRC configuration. In such embodiments, theindividual CCA starting or ending time for the group EDs can bedetermined every new cycle, based on the backoff counter value andwhether self-deferral is applied before or after CCA, respectively, suchthat the grant-free UL burst starts at the designated periodic instantfor that cycle.

Two or more GF ED groups, each configured to use a different GFtransmission cycle on the time-frequency resources of a given sub-band,can coexist in the same sub-band if they refer to the same GFtransmission cycle reference time, their GF transmission cycle periodsare integer multiples of the shortest GF transmission cycle periodamongst them, and their UL MCOTs are limited to the UL MCOT of theshortest GF transmission cycle period.

In some embodiments, a GF ED group configured to align their GFtransmission starting times to a common GF transmission cycle may beconfigured to start their GF transmissions at one of multiple GFoccasions within the GF cycle period. The occasion(s) within a GFtransmission cycle can be defined by default from the beginning of theGF cycle period or can be configured through high layer signaling, e.g.indicating an offset from the start of the GF transmission cycle. A GFoccasion may also be associated with a different set of GF parameterssuch as transport format, number of repetitions, frequencyinterlace/hopping patterns, etc. . . . . In such case, if one of the GFGEDs cannot start transmitting at the one of the occasion(s) due to afailed CAT2 LBT, for instance, it can defer the CAT2 LBT such that itmay start transmitting at a following occasion upon LBT success. If CAT4LBT is used instead, a GFG ED that cannot start transmitting at one ofthe occasions due to a failed CAT4 LBT may freeze its backoff counterand can either defer the CAT4 LBT and redo it using the frozen backoffcounter such that it may start transmitting at a following GF occasionupon LBT success, or it may keep performing the failing CAT4 LBTprocedure while freezing the backoff counter until LBT success isattained. However, if that successful CAT4 LBT finishes before one ofthe configured GF occasions, the ED may apply self-deferral such that itmay transmit at this GF occasion upon the success of another CCA withoutbackoff for a fixed duration, e.g., DIFS.

In some embodiments wherein a GF ED group are configured to start theirGF transmissions at one of multiple GF occasions within the GF cycleperiod, two or more GF ED groups, each configured to use the same GFtransmission cycle on the time-frequency resources of a given sub-band,can coexist in the same sub-band if they are configured to start theirGF transmissions based on different sets of occasions pre-configuredwithin the GF cycle period. The gNB may assign the different sets ofoccasions to the different coexisting GF ED groups based on whetherpartial contention-based or contention-free access is desired betweenEDs from different coexisting GF ED groups.

Grant-based uplink and downlink transmissions can coexist with thegrant-free uplink transmissions in the unlicensed spectrum sub-band byscheduling the GB transmissions such that they target the idle periodevery GF transmission cycle to avoid the resources already configuredfor GF transmissions. This can be achieved, for instance, by eitherscheduling the GB MCOT to end before the GF CCA procedure for the nextGF transmission cycle or by pre-emptively blanking the GB MCOT toaccommodate the GF CCA, the GF UL burst, and possibly a short time gap,within its duration. In the latter case, the grant can be accompanied,for instance, by a group common PDCCH using the GFG-RNTI to instruct theGF EDs to limit the current GF bursts, in compliance with theregulations, to an indicated length or to use a default length that hasbeen pre-configured earlier, e.g., through RRC signaling. In someembodiments, the medium access priority may be, in order from highest tolowest priority: UL GF transmissions>DL transmissions>UL GBtransmissions.

In some embodiments, a base station may transmit a switching grantmessage to a GF ED to indicate to the GF ED that a GB uplinktransmission has been scheduled for the GF ED. In addition to thetime-resources, the switching grant message may include information thatindicates: the transport block (TB)/HARQ process ID for which aretransmission is required or whether a new TB can be transmitted; anLBT category (e.g. CAT2 or CAT4); and a GB frequency region or sub-bandin which the GB uplink transmission for the ED has beenscheduled/granted. In such embodiments, if a GF ED receives such aswitching grant message, the GF ED transmits the TB using the LBTcategory and the GB frequency region or sub-band indicated in the grantmessage by the base station. If a GF ED is configured to use a GFtransmission cycle to access a given unlicensed spectrum sub-band forgrant-free uplink transmissions, the switching grant message mayindicate a different sub-band for the scheduled GB uplink transmissionfor the GF ED. This is to avoid regulatory issues if an ED is notallowed to access a given sub-band/channel/frequency region using thetwo medium access mechanisms, LBE and FBE, simultaneously. Forembodiments of the present disclosure in which a group of EDs areconfigured to align their GF transmission starting times for a givenunlicensed spectrum sub-band to a DL grant-free group (GFG) common timealignment signal, a base station may transmit the GFG common timealignment signal on the unlicensed spectrum sub-band following asuccessful LBT procedure, e.g., a CAT 4 LBT procedure. The GF EDs in theGFG align their GF transmission starting times by either transmittingdirectly without CCA after the end of the GFG common time alignmentsignal, if the time gap resulting from a boundary alignment requirement,e.g., symbol/slot/subframe alignment, is not longer than 16 μs, ortransmitting after the success of LBT CAT 2 (25 μs) immediatelyfollowing the end of the GFG common time alignment signal. In eithercase, with or without CCA, the aligned GF transmissions may start with areservation signal and/or a partial subframe to satisfy the boundaryalignment requirement.

In some embodiments, a base station may be configured to transmit theGFG common time alignment signal on a periodic/semi-periodic basis, i.e.transmit a periodic DL GFG common time alignment signal with a target GFcycle period following a successful LBT procedure, e.g., a CAT 2 LBTprocedure. In one embodiment, periodicity of the GFG common timealignment signal is preserved by the base station skipping thetransmission of the signal if the CCA fails for a given cycle period andtargeting the following GF cycle period. In such case, periodicity canalso be preserved even if a CAT 4 LBT procedure is used instead by thebase station determining the CCA starting time based on the randombackoff counter value every GF cycle period such that the DL GFG commontime alignment signal starts at the target periodic instants. In anotherembodiment, semi-periodic or pseudo-periodic transmission of the GFGcommon time alignment signal can be realized if the base stationpersistently performs CCA, according to either CAT2 or CAT4 LBT, fromthe beginning of the target GF cycle during a given time window that isshorter than the GF cycle period until CCA is successful or thetransmission is skipped for this period otherwise. Similarly, the GF EDsin the GFG align their GF transmission starting times by eithertransmitting directly without CCA after the end of theperiodic/semi-periodic GFG common time alignment signal, if the time gapresulting from the boundary alignment requirement is not longer than 16μs, or by aligning their CAT 2 LBT procedures to the end of the GFGcommon time alignment signal, if the time gap resulting from theboundary alignment requirement would be longer than 16 μs. In eithercase, with or without CCA, the aligned GF transmissions may start with areservation signal and/or a partial subframe to satisfy the boundaryalignment requirement, e.g., symbol/slot/subframe alignment. Theperiodic/semi-periodic nature of the GFG common time alignment signalallows for UL transmission of periodic sounding reference signals (SRS)or periodic channel state information (CSI) feedback in a best-effortmanner.

For embodiments of the present disclosure in which all or a sub-group ofthe GFG EDs align their GF transmission starting times for a givenunlicensed spectrum sub-band to a DL burst containing a CORESET thatincludes ED-specific DCI triggers, a base station may transmit theED-specific DCI triggers on the unlicensed spectrum sub-band following asuccessful LBT procedure, e.g., a CAT 4 LBT procedure. The triggered EDsalign their GF transmission starting times by either transmittingdirectly without CCA after the end of the signal containing theED-specific DCI triggers, if the time gap resulting from the boundaryalignment requirement is not longer than 16 μs, or by aligning their CAT2 LBT procedures to the end of the signal containing the ED-specific DCItriggers, if the time gap resulting from the boundary alignmentrequirement would be longer than 16 μs. In either cases, with or withoutCCA, the aligned GF transmissions may start with a reservation signaland/or a partial subframe to satisfy the boundary alignment requirement,e.g., symbol/slot/subframe alignment.

In some embodiments, a base station may transmit the ED-specific DCItriggers, to one or more of the GFG EDs, simultaneously with the DL GFGcommon time alignment signal to maintain the GF transmission alignmentand in the meanwhile can override the pre-configured GFG parameters,such as transport format, repetitions, frequency resources/hoppingpattern, etc . . . , for the one or more GFG EDs in accordance with thecontent of their individual triggers. In such cases,instructions/parameters received by an ED through an ED-specific triggermessage may be expected to override the correspondinginstructions/parameters received by the ED through the DL GFG commontime alignment message.

In some embodiments, a base station may transmit the ED-specific DCItriggers, to one or more of the GFG EDs such that the potential GFtransmissions of the one or more EDs are aligned with the GFtransmission starting time in one period of the pre-configured GFGtransmission cycle. In such cases, the GFG transmission alignment ismaintained while the pre-configured GFG parameters, such as transportformat, repetitions, frequency resources/hopping pattern, etc . . . ,for the one or more GFG EDs can be overridden in accordance with thecontent of the individual ED-specific triggers.

In some other embodiments, a base station may transmit the ED-specificDCI triggers to one or more of the GFG EDs independently from the DL GFGcommon time alignment signal or the GFG transmission cycle. Theindependent transmission of the ED-specific DCI triggers may be used bythe base station to accommodate increased UL traffic load of the one ormore GFG EDs or provide more frequent medium access opportunities, withrespect to the remaining GFG EDs, to meet higher QoS requirements ofindividual ED applications. The independent transmissions of theED-specific DCI triggers may be also used by the base station to alignthe UL GF transmissions of a given GFG on a given unlicensed sub-band inabsence of any GFG transmission cycle or any DL GFG common timealignment signals while possessing the capability of frequent overridingof the pre-configured GFG parameters for individual group EDs, e.g., asfrequent as the ED's UL GF transmissions.

Equipment that accesses unlicensed spectrum on a regular periodic basismust comply with FBE regulations to be able to use short one-shot LBT,e.g., CAT 2 LBT. However, because a DL GFG common time alignment signalcan potentially have a very short duration, the periodic/semi-periodicCCA/transmission associated with transmitting a periodic/semi-periodicDL GFG common time alignment signal with a target GF cycle period maynot need to comply with FBE regulations.

In some embodiments, the transmission of the GFG common time alignmentsignal (periodic, semi-periodic or aperiodic) and subsequent GF uplinktransmissions from GFG EDs may be realized as an UL-dominant subframewith the GFG common time alignment signal transmission within a DLportion of the UL-dominant subframe followed by the GF UL transmissionson respective pre-configured resources within an UL portion of theUL-dominant subframe. The use of a periodic, semi-periodic, or aperiodicGFG common time alignment signal to enable GF UL transmissionseliminates the contentions and delays for EDs to transmit a schedulingrequest and associated scheduling at a base station for grant-baseduplink transmissions, but may involve up to two LBT procedures before aGF uplink burst can be transmitted.

Sub-band time-frequency resources are shared by the group EDs for theirrespective grant-free uplink transmissions within the sub-band, butbecause the CCAs of group EDs are aligned in time the group EDs do notblock each other during the CCA procedure.

In some embodiments, EDs can apply either a random or a pre-configuredoccupational bandwidth-compliant (OCB-compliant) frequency-hoppingpattern within the time-frequency resources of the sub-band forcontrolled collisions and frequency diversity. An example ofOCB-compliant frequency-hopping pattern is a random or a pre-configuredsequence of frequency interlaces to be used by the ED over consecutiveslots of the GF transmission. In some embodiments, a subset of GF EDs ina given sub-band can be configured to persistently collide (occupy thesame time-frequency resources) whenever transmitting concurrently, e.g.,given spatial/code domain (pseudo-)orthogonality and/or power offset sothat the base station can distinguish and separate their respective GFuplink transmissions. For example, such a subset of EDs may receive acommon seed value from the base station to use along with a commonrandom number generator to generate, every alignment time unit (ATU),e.g., slot or subframe, the same random frequency interlace/unlicensedchannel index to determine the specific time-frequency resources to beused for transmission in a given ATU regardless of whether or not the EDactually has a transmission to make for the given ATU. As in GF uplinktransmission in the licensed spectrum, in embodiments of the presentdisclosure intra-hyper-cell contention/collision is allowed according tothe GF configuration.

In some embodiments, a multi-cast GFG feedback message may betransmitted by a base station in the unlicensed spectrum in order toprovide feedback to GF EDs in a GFG. For example, the GFG feedbackmessage may include Acknowledgement/Negative Acknowledgement (Ack/Nack)feedback. The GFG feedback message may be transmitted by the basestation using group common DCI and the GFG-RNTI, for example.

As will be discussed in further detail later on, a GFG feedback messagemay be transmitted by a base station after a short time gap, e.g., lessthan 16 μs, following the longest in-group GF transmission and within amaximum channel occupancy time (MCOT) time span. In embodiments thatutilize a common time alignment signal, a GFG feedback message may beincluded within the DL common time alignment signal, and may be inreference to the GF UL burst in a previous transmission. RRC signalingprior to the transmission of the GFG feedback message may be used toinform the GF EDs of their respective fields in the group commonfeedback message. A filed could be multiple bits corresponding tomultiple TBs/code blocks groups (CBGs) in the ED group common Ack/Nackfeedback message.

In some embodiments, the GFG feedback message may also or insteadinclude GFG Dynamic Closed Loop Link Adaptation (DCLLA) commands and/orClosed Loop Power Control (CLPC) commands. For example, in someembodiments, GFG DCLLA commands and/or CLPC commands may be appended toor combined with the GFG common Ack/Nack feedback as an augmentedfeedback message format.

In some embodiments, ED-directed link adaptation may be supported, andin such embodiments the GFG feedback message may also or instead includeUL channel state information (CSI) feedback.

In other embodiments, GFG Ack/Nack feedback may also or instead betransmitted over a PHICH-like channel. In such embodiments, RRCsignaling prior to the feedback transmission may be used to inform theGF EDs of respective physical resources that will be used to transmittheir respective GFG Ack/Nack feedback.

A numerology is defined as the set of physical layer parameters of theair interface that are used to communicate a particular signal. ForOFDM-based communication, a numerology is described in terms of at leastsubcarrier spacing (SCS) and OFDM symbol duration, and may also bedefined by other parameters such as fast Fourier transform (FFT)/inverseFFI (IFFT) length, transmission time slot length, and cyclic prefix (CP)length or duration. As will be discussed in further detail later on, thenumerologies used for GF UL transmissions in the unlicensed spectrum inaccordance with the present disclosure may be selected so as to supportcertain functionality. For example, in some embodiments the numerologyselected for GF UL transmission in a given unlicensed spectrum sub-bandmay include/provide a large enough SCS and/or long MCOT to allow for aconfigurable number of K repetitions of a TB, with or withoutfrequency-hopping, to occur within a GF UL burst in order to increasethe likelihood of successful decoding. Such repetitions can potentiallysupport applications with high reliability requirements.

Similarly, in some embodiments a GF ED can start transmitting a new TBupon packet arrival during a GF UL MCOT without waiting for a new CCA,which can potentially support applications with low latencyrequirements. For example, a GF ED may begin transmitting a second TBimmediately after completing the repetitions of a first TB or during therepetitions of the first TBs using, e.g., first and second orthogonalfrequency interlaces per slot/mini-slot for transmission of therepetitions of the first and second TBs within the same slot/mini-slot.

In some embodiments, a GF ED may start its GF UL burst with an ULcontrol signal, e.g., wide band Physical Uplink Control Channel (PUCCH)carrying Uplink Control Information (UCI) such as ED ID, modulation andcoding scheme (MCS) used for ED-directed link adaptation, and/or UL HARQinformation (e.g., HARQ ID, New-Data Indicator (NDI), etc.). In someembodiments, the GF Physical Uplink Shared Channel (PUSCH) ismultiplexed with an ED-specific or TB-specific reference signal, e.g.,front-loaded DMRS. The base station may use the combination of RS andoccupied time-frequency resources to identify the GF ED or the furtheridentify its TB/HARQ process ID. To support the GF transmission ofmultiple TBs simultaneously, a gNB needs to identify and soft-combinetransmissions and repetitions of each TB. In such cases, an ED may beconfigured to use multiple RSs, each with a given TB (i.e. TB-specificRSs), or configured to use one RS and multiple T/F resource sets, eachfor a given TB. A combination of the above is also possible.

As noted above, in some embodiments of the present disclosure a basestation transmits group-specific configuration information to be used byEDs in the group for alignment of their GF transmissions to accesstime-frequency resources of an unlicensed spectrum sub-band. Forexample, the group-specific configuration information may be transmittedto GF EDs in the group via RRC signaling that includes a GFG-RNTIassociated with the group, an unlicensed GFG sub-band indication thatindicates the unlicensed spectrum sub-band to be used by the GFG of EDsfor GF UL transmission, a frequency hopping pattern/seed value ofOCB-compliant transmissions/repetitions over the sub-band, andinformation indicating an ED-dedicated field format in GFG common DCImessage (e.g., for a GFG common feedback message and/or GFG common timealignment message).

In some embodiments, the RRC signaling may also explicitly indicate theSCS and/or CP type for the unlicensed spectrum sub-band, e.g., if theSCS and/or CP type is not deducible from the GFG sub-band indication.

The information indicating a frequency hopping pattern/seed value ofOCB-compliant transmissions/repetitions over the sub-band may indicate asequence of frequency interlaces to use, a sequence of unlicensedchannels to occupy, or a combination of interlaces and channels.Alternatively, a subset of the GFG EDs may receive a common seed torandomly generate the frequency interlace/unlicensed channel index touse every ATU (e.g., slot or subframe) regardless of whethertransmitting a GF UL burst or not. In such embodiments, GF UL burststransmitted by the subset of GF EDs that receive the same common seedwill occupy the same T/F resources whenever transmitted concurrently,but spatial/code domain (pseudo-)orthogonality and/or power offset maybe used to allow the base station to be able to distinguish and separatethe respective GF uplink transmissions.

The information indicating the ED dedicated field format in the GFGCommon DCI message may include information indicating the number ofunlicensed channels on which the GFG DCI message is distributed for OCBcompliance. In some embodiments the information may also or insteadindicate ED sub-fields, e.g., if GFG feedback is augmented, i.e., groupAck/Nack, CLPC and/or DCLLA commands, or UL CSI feedback, as describedpreviously.

GFG Configuration Information for Common GF Transmission Cycle

As noted above, in some embodiments a group of EDs are configured toalign their GF transmission starting times to a common GF transmissioncycle characterized by a GF transmission cycle reference time and a GFtransmission cycle period. In such embodiments, the group-specificconfiguration information further includes information indicating the GFtransmission cycle reference time, GF transmission cycle period and amaximum GF burst length.

The GF transmission cycle period and maximum GF burst length may beindicated explicitly in the configuration information, e.g., the numberof OFDM symbols (OSs), slots or mini-slots, or the configurationinformation may include a configuration index or a priority class indexthat can be used by the EDs to look up this pair of parameters given aparticular frame structure type and SCS/CP type, as will be discussed infurther detail later on with reference to the tables shown in FIGS.10A-10D and 11A-11D.

The GF transmission cycle reference time can be indicated as a relativeoffset w, i.e., the number of OSs, slots, or mini-slots from the end ofan RRC PDSCH transmission that may also include the GFG configurationinformation message. For example, FIG. 3A is a timing diagram showing anexample of RRC signaling under a DL HARQ procedure, wherein the RRCsignaling includes an indication of an offset w to configure agrant-free common transmission cycle in accordance with an embodiment ofthe present disclosure.

For example, if the DL HARQ procedure had a 1^(st) retransmissioninterval T1>w (not shown in FIG. 3A), a GF ED may adjust the offset wextracted from a successful 1^(st) retransmission (as shown at 302) topoint at the next cycle reference time as w←w+(GF Transmission CyclePeriod—T1). Otherwise, as shown in the upper scenario shown in FIG. 3A,if T1<w, then w←w—T1 (as shown at 303). An ED may determine theretransmission interval T1 by measuring the time difference between theend of the initial RRC PDSCH transmission and the end of the 1^(st) RRCPDSCH re-transmission.

Furthermore, as shown in the lower scenario shown in FIG. 3A, if the DLHARQ procedure had a 2^(nd) retransmission interval such that T1+T2>w, aGF ED may adjust the offset w extracted from the successful 2^(nd)retransmission (as shown at 304) to point at the next cycle referencetime as w←w+(c*GF Transmission Cycle Period—(T1+T2)) (as shown at 305),where c=floor((T1+T2)/GF Transmission Cycle Period) and floor ( ) is thefloor function. Otherwise, if T1+T2<w (not shown in FIG. 3A), thenw←w—(T1+T2), and so on for subsequent retransmissions of the RRC PDSCHmessage that includes the group-specific configuration information.

If no DL HARQ is applied to the RRC PDSCH, or the DL HARQ process hasexhausted a maximum number of permitted retransmissions, a base stationmay re-encode the RRC message after revising the offset w in referenceto the next earliest GF transmission cycle reference time.

In another embodiment, the GF transmission cycle reference time can beindicated as an absolute index within the current system frame number(SFN), i.e., index of the OS, slot, or mini-slot at which the GFtransmission cycle can start in the current SFN. In such case, the RRCPDSCH carrying the absolute index, which may also include the GFGconfiguration information message, remains the same over DL HARQretransmissions within the same SFN, and thus soft combining is possibleat the ED. For example, FIG. 3B is a timing diagram showing an exampleof RRC signaling under a DL HARQ procedure, wherein the RRC signalingincludes an indication of the absolute time index t₀ to configure agrant-free common transmission cycle in accordance with an embodiment ofthe present disclosure.

For example, if the DL HARQ procedure had a 1^(st) retransmission, a GFED may set the GF cycle reference time to t₀ as extracted from a 1^(st)retransmission successfully decoded at time index t (as shown at 312).However, if t>(t₀+GF Transmission Cycle Period), the GF cycle referencetime can be increased iteratively by the GF Transmission Cycle Perioduntil it is equal to or greater than the time index t. Furthermore, asshown in the lower case of FIG. 3B, if the ED fails to acknowledgesuccessful decoding of the RRC message sent in SFN n, for instance, thebase station may re-encode the RRC message into a new PDSCH afteradjusting the absolute time index to point to the next earliest GF cyclereference time t₁ in SFN n+1 (as shown at 314) and so on.

In another embodiment, the GF transmission cycle reference time may notbe indicated in a relative or absolute manner but rather implicitlydeduced from the GF transmission cycle period. The time synchronizationinformation that is common to all the GFG EDs, such as the SFN orsubframe/slot number, can be used by the GFG EDs to deduce the GFtransmission cycle reference time. For example, the GF ED can set its GFtransmission cycle reference time to the subframe that satisfies theformulae, mod(Subframe Number, GF Cycle Period)=q, whereas GF CyclePeriod is an integer number of subframes and q=0, 1, . . . , GF CyclePeriod-1 is a GFG-specific parameter configurable through RRC signaling,for instance. In such case, two or more GF ED groups configured to usedifferent GF transmission cycles of the same cycle period, can coexistin the same sub-band if they are configured to use different values ofthe q parameter.

In some embodiments, the group-specific configuration information mayalso include a GF frame structure type/index that indicates apredetermined GF frame structure that is to be used for GF ULtransmission in the selected unlicensed spectrum sub-band. Examples ofsuch frame structures are shown in FIGS. 4A and 4B. Each of theillustrated frame structures may be associated with a respective GFframe structure index value, and a base station may signal the GF framestructure type that is to be used by transmitting the corresponding GFframe structure index value as part of the group-specific configurationinformation.

GF Frame Structure Design for Common GF Transmission Cycle

The following factors may be considered in the design of the GF framestructure with an FBE-compliant GF transmission cycle in the unlicensedspectrum:

FBE regulatory requirements

Desired UL GF MCOT depending on

Desired UL burst length based on

Numerology of the unlicensed sub-band (e.g., SCS/OS duration, CP length)

Pre-configured TB transmission duration (e.g., in terms of number ofOFDM symbols (OSs), which depends on a preconfigured TB size, the numberof time-frequency resource elements per TB, and demodulation referencesignal (DMRS) overhead)

Number of GF repetitions per TB

DL GFG feedback length, if any (e.g., in terms of number of OSs)

Desired ATU (e.g., slot, mini-slot, symbol)

Whether CCA occurs immediately before or immediately after the beginningof the new GF transmission cycle Period (for coexistence with otherintra-base station DL/GB UL transmissions in the same sub-band).

Four examples of GF frame structures that were designed taking intoconsideration the aforementioned factors are shown in FIGS. 4A and 4B.In particular, FIGS. 4A and 4B are timing diagrams showing four examplesof GF frame structures A, B, C and D for grant-free uplink transmissionin an unlicensed spectrum sub-band based on a common GF transmissioncycle in accordance with example embodiments of the present disclosure.In the GF frame structures A and B shown in FIG. 4A the CCA is performedat the end of the GF transmission cycle period meaning that theassociated GF transmission can start at the beginning of the followingGF transmission cycle period upon CCA success, whereas the CCA isperformed at the beginning of the GF transmission cycle period in the GFframe structures C and D shown in FIG. 4B meaning that the associated GFtransmission can start after the beginning of the same GF transmissioncycle period upon CCA success in accordance with the boundary alignmentrequirement, e.g., symbol/slot/mini-slot. Performing the CCA at thebeginning of the GF transmission cycle period can potentially providemore CCA protection from coexisting transmissions managed by other basestations within the idle period at the end of the GF transmission cycleperiod. However, this potential increased protection comes at theexpense of increased reservation overhead because the CCA occurs withinthe GF transmission cycle period and occupies a portion of the UL MCOTtime span.

Referring to FIG. 4A, it is noted that frame structure B differs fromframe structure A in that it includes a provision for DL GFG feedback tobe transmitted by the base station at the end of the UL MCOT. In GFframe structure B, after a GF ED has finished transmitting its UL burstit may transmit a partial subframe at the ATU boundary followed by areservation signal to act as “reservation” of the unlicensed spectrumsub-band (i.e. to act as interference to prevent other device's CCA'sfrom seeing the unlicensed spectrum sub-band as being available duringthe UL MCOT). As such, the base station's downlink transmission of theDL GFG feedback can begin at the next ATU (e.g., slot, mini-slot,symbol) after a short time gap following the end of the reservationsignal, RSRV. In some embodiments with relatively long OS duration, theRSRV duration is set to the OS duration less the short time gap suchthat the total duration of the partial subframe, the RSRV and the shorttime gap is equal to the ATU duration.

Referring to FIG. 4B, it is noted that, following a successful CCA, areservation signal (RSRV) and a partial subframe are transmitted at thebeginning of UL MCOT in both frame structures C and D so that thetransmission of the UL burst begins at the next ATU following thesuccessful CCA. In some embodiments with relatively long OS duration,the RSRV duration is set to the OS duration less the CCA duration suchthat the total duration of the CCA, the RSRV, and the partial subframeis equal to the ATU duration. Frame structure D differs from framestructure C in that it includes a provision for DL GFG feedback, DL GFGFB, to be transmitted by the base station at the end of the UL MCOT. InGF frame structure D, after a GF ED has finished transmitting its ULburst it transmits a partial subframe followed by a reservation signalfor the same reasons as discussed above with respect to frame structureB. Similar to the frame structure B, in the frame structure D the basestation's downlink transmission of the DL GFG feedback begins at thenext ATU after a short time gap (STG) following the end of thereservation signal, RSRV.

The example GF frame structures A, B, C and D show ATU>CCA>short timegap. More generally, the ATU could be an OS, a slot, a mini-slot, orsubframe.

For a base station to provision for DL critical/periodic signals, suchas discovery reference signal (DRS) and paging, in the same unlicensedspectrum sub-band as GF UL transmissions, the target DL transmissionperiod, e.g., the target DRS period, can be configured as an integermultiple of the GF Transmission Cycle Period and the GF TransmissionCycle Reference Time can be set such that the DL transmission fallswithin the idle period of the GF Transmission Cycle. Similarly,intra-base station coexisting DL or GB UL transmissions can bedynamically scheduled in the same unlicensed spectrum sub-band as GF ULtransmissions so that the coexisting DL or GB UL transmissions start inthe idle period and end before the CCA of a new GF Transmission Cycle.Another way of achieving such coexistence is by pre-emptively blankingthe GB MCOT to accommodate the GF CCA, the GF UL burst, and possibly anRSRV followed by a short time gap, within its duration. In the lattercase, the DL/GB UL grant can be accompanied, for instance, by a groupcommon PDCCH using the GFG-RNTI to instruct the GF EDs to limit thecurrent GF bursts, in compliance with the regulations, to an indicatedlength or to use a default length that has been pre-configured earlier,e.g., through RRC signaling.

FIG. 5 is a table showing examples of reservation overhead associatedwith the four frame structures A, B, C and D shown in FIGS. 4A and 4B,where reservation overhead is defined as the relative portion of the ULMCOT time span that is not used by the GF UL burst transmission. Inparticular, the table in FIG. 5 shows examples of reservation overheadassociated with the four frame structures A, B, C and D for variousrelative lengths of OFDM symbol durations (OS), short time gapdurations, and CCA durations (CCA). It is noted that in the table shownin FIG. 5 , ceil( ) is the ceiling function and the notation “B+C” isused to indicate that the reservation overhead for frame structure D isthe sum of the reservation overheads for frame structures B and C. It isfurther noted that the reservation overhead increases for each of theframe structures from frame structure A to frame structure D, with framestructure A having no reservation overhead and frame structure D havingthe most reservation overhead.

In some embodiments, in addition to the GF frame structure type/indexthe group-specific configuration information may also include anindication of ATU, short time gap, CCA, and DL GFG Feedback durations(if different from default values).

FIGS. 6A and 6B are timing diagrams showing an example of two GFtransmission cycles of different periods and reference times being usedon two different unlicensed spectrum sub-bands in accordance with anembodiment of the present disclosure. In particular, FIG. 6A is a timingdiagram showing an example of unlicensed spectrum access procedures byfirst and second UEs, GF UE1 and GF UE2, configured to align theirtransmission starting times based on a first common GF transmissioncycle to access a first unlicensed spectrum sub-band, UnlicensedSub-band 1, for grant-free uplink transmission and FIG. 6B is a timingdiagram showing an example of unlicensed spectrum access procedures bythird and fourth UEs, GF UE3 and GF UE4, configured to align theirtransmission starting times based on a second common GF transmissioncycle to access a second unlicensed spectrum sub-band, UnlicensedSub-band 2, for grant-free uplink transmission.

It is noted that the GF UL transmissions shown in FIGS. 6A and 6B alluse a frame structure type that is similar to the frame structure Ashown in FIG. 4A, i.e., CCA at the end of the GF transmission cycle andno DL GFG feedback. However, the first common GF transmission cycle usedby the first and second UEs in the first unlicensed spectrum sub-band inFIG. 6A is slot aligned (i.e. ATU=slot) with a GF transmission cycleperiod of 9 slots, and the second common GF transmission cycle used bythe third and fourth UEs in the second unlicensed spectrum sub-band inFIG. 6B is symbol aligned (i.e. ATU=OS) with a GF transmission cycleperiod of 30 OSs.

It is also noted that the unlicensed spectrum procedures performed by GFUE1 and GF UE2 in Unlicensed Sub-band 1 are performed for/on the sametime-frequency resources of Unlicensed Sub-band 1, but they have beenshown separately in FIG. 6A so as to illustrate their features moreclearly. The unlicensed spectrum procedures performed by GF UE3 and GFUE4 in Unlicensed Sub-band 2 are also performed for/on the sametime-frequency resources of Unlicensed Sub-band 2, but are shownseparately in FIG. 6B for the same reason.

As noted above, and shown by way of example in FIGS. 6A and 6B, in someembodiments of the present disclosure a GF UE may transmit multiplerepetitions of a given TB within a GF UL burst, and may do so for morethan one TB. For example, referring to FIG. 6A, it can be seen thatafter performing a successful LBT CAT 2 CCA, GF UE1 transmits fourrepetitions of two TBs, UE1 TB1 and UE1 TB2 within the GF UL burst thatit transmits in the first GF transmission cycle period I. GFtransmission cycle period I is nine slots long.

In both FIG. 6A and FIG. 6B the minimum idle period is configured to be5% of the maximum GF burst length. For example, in FIG. 6A, the minimumidle period is 50 μs, which is 5% of the 1 ms maximum GF burst length.Similarly, in FIG. 6B, the maximum GF burst length is 2 ms and theminimum idle period is 100 μs.

As noted above, the GFGs of UEs share the time-frequency resources oftheir respective sub-bands, i.e., GF UE1 and GF UE2 share thetime-frequency resources of Unlicensed Sub-band 1 and GF UE3 and GF UE4share the time-frequency resources of Unlicensed Sub-band 2. However,that does not necessarily mean that the respective GF UL bursts within agiven sub-band overlap on all of the same time-frequency resourceswithin the sub-band. For example, the GF UL bursts transmitted by GF UE1in the first and second GF transmission cycles shown in FIG. 6A occupy acontiguous band of time-frequency resources within Unlicensed Sub-band1. In contrast, the GF UL bursts transmitted by GF UE 2 in the first andsecond GF transmission cycles shown in FIG. 6A occupy twofrequency-separated bands of time-frequency resources within UnlicensedSub-band 1. As another example, referring to FIG. 6B, it can be seenthat GF UE3 and GF UE4 each use frequency interlace hopping whentransmitting their respective GF UL bursts. That is, GF UE3 and GF UE4each use a respective sequence of frequency interlaces to transmit theirrespective GF UL bursts within Unlicensed Sub-band 2 during one GFtransmission cycle. In particular, GF UE3 uses a sequence of frequencyinterlaces that follows a pattern of Interlace 1, Interlace 2, andInterlace 1 over the course of three slots to transmit three repetitionsof one TB, UE3 TB1, while GF UE4 uses a sequence of frequency interlacesthat follows a pattern of Interlace 3, Interlace 2, Interlace 3, andInterlace 1 over the course of four slots to transmit two repetitionseach of two TBs, UE4 TB1 and UE4 TB2 within Unlicensed Sub-band 2 duringone GF transmission cycle.

As noted above, the GF UL transmissions shown in FIGS. 6A and 6B all usea frame structure that is similar to the frame structure A shown in FIG.4A. FIGS. 7A and 7B are timing diagrams showing another example of twoGF transmission cycles of different periods and reference times beingused on two different unlicensed spectrum sub-bands similar to theexamples shown in FIGS. 6A and 6B, but in FIGS. 7A and 7B the GF ULtransmissions use a frame structure that is similar to the framestructure B shown in FIG. 4A, i.e., CCA at the end of the GFtransmission cycle with reservation signals terminating the end of theGF UL bursts and DL GFG feedback transmitted by the base station after ashort time gap from the end of the longest GF UL transmission and beforethe end of the MCOT. One key difference though in the examples of FIGS.7A and 7B from the more general frame structure B in FIG. 4A is that theDL GFG is required to align to the OS boundary and thus a partialsubframe is not required. As a result of the additional reservationoverhead associated with this frame structure, it is noted that the GFtransmission cycle period I used in Unlicensed Sub-band 1 is increasedto 11 slots in FIG. 7A compared to 9 slots in FIG. 6A.

Once a GF UL burst ends, a GF ED configured to use a type B/D framestructure, such as GF UE1, UE2, UE3 and UE 4 shown in FIGS. 7A and 7Btransmits a reservation signal for a duration as discussed above withrespect to FIGS. 4A and 4B.

In some embodiments, the GF ED follows by monitoring the common searchspace for DL GFG feedback only at the beginning of each OS or each ATUwithin the remaining time span of the MCOT and using the GFG-RNTI toidentify the DL GFG feedback for the GFG to which it belongs.

In other embodiments, the GF ED may extend its GF transmission to occupythe maximum portion of configured UL MCOT so that the GFG Feedback timeis known a priori, and hence, the computational complexity of the GF EDsearching the common search space using the GFG-RNTI may be reduced.There are multiple ways in which a GF burst can be extended. Forexample, one option would be to extend the reservation signal at the endof the GF UL burst until it partially occupies the ATU in which theshort time gap is applied according to the configured UL MCOT. A secondoption would be to exceed the number of pre-configured GF repetitions sothat the GF UL burst occupies the ATUs until the one containing theshort time gap according to the configured UL MCOT. A third option wouldbe a combination of the first two options. A fourth option would be tooverride the pre-configured GF transport format and perform ratematching to occupy the ATUs until the one containing the short time gapaccording to the configured UL MCOT, i.e., employing a lower MCS. Thenew MCS could be indicated to the base station in a wideband PUCCHcarrying UCI at the beginning of the GF UL Burst, for example. Anotheroption to indicate, or at least narrow down the base station's blinddetection required to identify, the new MCS would be to transmit afront-loaded pilot or DMRS that differs from a default pilot or DMRS.The transmission of the different pilot of DMRS could explicitlyindicate or narrow down the possible new MCS, or it may instead indicatea scaling factor between the original GF burst length and therate-matched length according to the configured MCOT. A third option toindicate the new MCS to the base station would be to transmit an UL RRCsignal, using the pre-configured MCS according to the pre-configured GFtransport format, before the useful portion of the GF UL burst, e.g.,during or instead of the 1^(st) reservation/partial subframe signal inframe structure type D, to indicate the new rate matching MCS. The ULRRC signal may instead indicate the scaling factor between original GFburst length and the rate-matched length according to the configuredMCOT.

GFG Feedback Contents and Transmission for Common GF Transmission Cycle

For embodiments of the present disclosure in which a group of EDs areconfigured to align their GF transmission starting times to a common GFtransmission cycle characterized by a GF transmission cycle referencetime and a GF transmission cycle period, the GFG DCI message transmittedas part of the GFG feedback message may contain one or more of thefollowing as feedback from the base station: GFG Ack/Nack feedback; aMCS increase/decrease command for base station-directed DCLLA or UL CSIfeedback for ED-directed link adaptation; a Transmit Power Control (TPC)increase/decrease command, e.g., if DCI format 3/3A is not employedseparately. The GFG feedback message may include M ED-specific fieldsthat include information bits that provide the foregoing ED-specificfeedback(s), where M is the number of GF EDs in the GFG.

FIG. 8 is a block diagram of an example encoder for forming a grant-freegroup feedback message in accordance with an embodiment of the presentdisclosure. The encoder is implemented with a cyclic redundancy check(CRC) encoder that takes the bits of M ED-specific fields and uses theGFG-RNTI to generate a CRC code that it appends to the M ED-specificfields to form the GFG feedback message. As such, only in-group EDssharing the GFG-RNTI can decode the DL GFG feedback message.

The ED-specific Ack/Nack filed within the GFG feedback may includemultiple bits (L), where L may be as large as the maximum number of TBsthat can be transmitted during the maximum GF burst length, e.g., basedon TB duration and the number of repetitions K. Alternatively, L may beas large as the maximum number of code block groups (CBGs) that can betransmitted during the maximum GF burst length. If decoding delayprecludes feeding back Ack/Nack feedback for some GF transmission(s) atthe end of the longest burst, especially if low-density parity-check(LDPC) is not used, the L bits of Ack/Nack feedback may include L-m bitsfrom the current GF burst and m bits from the previous GF burst. Theparameter m may be ED-specific, determined by the base station based onthe ED's capability and sent to the ED within the RRC configurationmessage as part of the format information of its dedicated field in theDL GFG feedback. The base station can determine m for each ED as followsfor instance; m=ceil (CBG decoding delay/CBG Tx duration), where ceil( )is the ceiling function, CBG decoding delay is the decoding delayassociated with the ED's decoding a CBG, and CBG Tx duration is the timeduration associated with transmission of a CBG by the ED according tothe pre-configured resources and transport format.

In general, there are two ways GFG feedback may be transmitted. A firstoption is to transmit GFG feedback separately, without multiplexing withother DL control and data. In such cases, no LBT is required. However,the GFG feedback data should be at least distributed to a minimumchannel bandwidth in order to comply with OCB regulatory requirements,if applicable. A second option is to transmit GFG feedback together withother DL control and data, e.g., other PDCCH and PDSCH with no specificrequirement in resource mapping for the GFG feedback data. In suchcases, LBT is required together with the downlink transmission.

In some embodiments, the physical time-frequency resources used totransmit the GFG DCI message may be distributed over a single unlicensedchannel of the GF sub-band, e.g., over a single 20 MHz unlicensedchannel, according to a Interleaved Frequency Division Multiple Access(IFDMA) scheme with interleaved tones, a resource block (RB) interlacescheme, or as multi-clustered RBs. Alternatively, the number ofunlicensed channels of the GF sub-band on which the GFG DCI message aredistributed may depend on the message size (M, L_(A/N), L_(TPC),L_(DCLLA)) and the mapping to control channel elements (CCEs). Thisnumber may be indicated to GF EDs in an RRC signal, for example.

As noted previously, there may be various circumstances in which it isdesirable to switch a GF ED from contention-based GF uplink transmissionto GB uplink transmission, e.g., for the retransmission of a TB. Forexample, for a GF ED experiencing bad channel conditions and/orpersistent harmful collisions, switching a TB to contention-free GBtransmission is often desired to ensure successful decoding and/or toexploit link adaptation of uplink scheduling by the base station.Therefore, in some embodiments, a base station may transmit a switchinggrant message to a GF ED to indicate to the GF ED that a GB uplinktransmission has been scheduled for the GF ED for retransmission of aTB.

FIG. 9 is a timing diagram showing an example of a first ED that isconfigured to align its GF transmission starting time to a first commonGF transmission cycle to access a first unlicensed spectrum sub-band forgrant-free uplink transmission being granted an uplink transmissiongrant for a second unlicensed spectrum sub-band, in accordance with anembodiment of the present disclosure. In the example scenario shown inFIG. 9 , a first group of three UEs, namely GF UE1, GF UE3 and GF UE4,have been configured to align their GF transmission starting times to afirst common GF transmission cycle to access a first unlicensed spectrumsub-band, namely Unlicensed Sub-band 1, for GF uplink transmission, anda second group of three UEs, namely GF UE2, GF UE5 and GF UE8, have beenconfigured to align their GF transmission starting times to a secondcommon GF transmission cycle to access a second unlicensed spectrumsub-band, namely Unlicensed Sub-band 2, for GF uplink transmission. Itis noted that the first and second common GF transmission cyclesconfigured for the two Unlicensed sub-bands are asynchronous, i.e., theyfeature different reference times and/or different cycle periods.

As shown in FIG. 9 , GF UE1 receives a switching grant message from abase station/gNB within the Idle Period of the first common GFtransmission cycle configured for Unlicensed Sub-band 1; the DLresources used for transmitting the grant are not shown though. Theswitching grant message indicates that GF UE1 has been granted ascheduling grant for a GB UL transmission in Unlicensed Sub-band 2. TheGB UL transmission may be for the retransmission of a TB that waspreviously transmitted by GF UE 1 via GF UL transmission in UnlicensedSub-band 1, for example. The previously transmitted TB may have beentransmitted by GF UE 1 in the GF UL burst immediately preceding the IdlePeriod in which the switching grant message is received, or it may havebeen previously transmitted in an earlier GF UL burst. The GB ULtransmission for GF UE 1 has been scheduled by the base station so thatit targets the Idle Period of the second common GF transmission cycleconfigured for Unlicensed Sub-band 2. In accordance with the switchinggrant message, GF UE 1 subsequently performs a CCA procedure to accessthe time-frequency resources of Unlicensed Sub-band 2 in order totransmit the scheduled GB uplink transmission. In some embodiments, theCCA procedure for GB UL transmission may be different than the CCAprocedure for GF UL transmission. For example, GF UE 1 may be configuredto perform an FBE-compliant LBT CAT2 CCA procedure for its GF UL bursttransmissions in Unlicensed Sub-band 1, and be configured to perform anLBE-compliant LBT CAT4 CCA for its GB UL burst transmission inUnlicensed Sub-band 1. In some embodiments, the switching grant messagemay include information that indicates an LBT category (e.g. CAT2 orCAT4) and a GB frequency region or sub-band in which the GB uplinktransmission for the ED has been scheduled/granted. In some otherembodiments, the grant message may indicate that the ED is allowed totransmit a new TB according to the granted resources and LBT typeindicated.

GF Transmission Cycle Numerology

As noted above, and shown by way of example in FIGS. 6A, 6B, 7A, 7B and9 , the aligned GF transmission cycles used by a group of GF EDs for agiven unlicensed spectrum sub-band can be asynchronous with respect tothe aligned GF transmission cycles used for other unlicensed spectrumsub-band(s), and the respective numerologies and ATUs used in differentunlicensed spectrum sub-bands may also be different. For example,referring to FIGS. 6A and 7A, the sub-band numerology used in UnlicensedSub-band 1 is shown as having a 60 KHz SCS. In contrast, referring toFIGS. 6B and 7B, the sub-band numerology used in Unlicensed Sub-band 2is shown as having a 15 kHz SCS.

Frame structures have been proposed that are flexible in terms of theuse of differing numerologies. As previously noted, a numerology isdefined as the set of physical layer parameters of the air interfacethat are used to communicate a particular signal. A numerology isdescribed in terms of at least SCS and OFDM symbol duration, and mayalso be defined by other parameters such as fast Fourier transform(FFT)/inverse FFI (IFFT) length, transmission time slot length, andcyclic prefix (CP) length or duration. In some implementations, thedefinition of the numerology may also include which one of severalcandidate waveforms is used to communicate the signal. Possible waveformcandidates may include, but are not limited to, one or more orthogonalor non-orthogonal waveforms selected from the following: OrthogonalFrequency Division Multiplexing (OFDM), Filtered OFDM (f-OFDM), FilterBank Multicarrier (FBMC), Universal Filtered Multicarrier (UFMC),Generalized Frequency Division Multiplexing (GFDM), Single CarrierFrequency Division Multiple Access (SC-FDMA), Low Density SignatureMulticarrier Code Division Multiple Access (LDS-MC-CDMA), Wavelet PacketModulation (WPM), Faster Than Nyquist (FTN) Waveform, low Peak toAverage Power Ratio Waveform (low PAPR WF), Pattern Division MultipleAccess (PDMA), Lattice Partition Multiple Access (LPMA), Resource SpreadMultiple Access (RSMA), and Sparse Code Multiple Access (SCMA).

These numerologies may be scalable in the sense that subcarrier spacingsof different numerologies are multiples of each other, and time slotlengths of different numerologies are also multiples of each other. Sucha scalable design across multiple numerologies provides implementationbenefits, for example scalable total OFDM symbol duration in a timedivision duplex (TDD) context.

The 3GPP Release 14 specification discussed earlier includes channelaccess priority classes for devices accessing a physical uplink sharedchannel (PUSCH) using LTE-based eLAA. In some embodiments of the presentdisclosure, unlicensed channel access priority classes for accessingunlicensed spectrum for GF UL transmission may similarly be defined byadopting the same values specified for Release 14 eLAA PUSCH MCOT,T_(ulmcot,p), per channel access priority class index, p, among thedesign values to achieve the minimum GF Transmission Cycle, i.e., withthe most frequent medium access attempts. FIGS. 10A, 10B, 10C, 10D, 11A,11B, 11C and 11D depict tables that include examples of unlicensedchannel access priority classes that are mapped to priority classindices in accordance with such embodiments. In particular, FIGS.10A-10D depict four tables showing priority classes and associatedchannel access parameters\numerologies based on the four framestructures A, B, C and D of FIGS. 4A and 4B for different sub-band SCSsand cyclic prefix lengths in a 5 GHz unlicensed spectrum band, and FIGS.11A-11D depict a further four tables showing similar priority classesand associated numerologies in a 60 GHz unlicensed spectrum band.

In order to comply with the European FBE regulatory requirementsdiscussed earlier, the following design rules were used to determine thepriority classes and associated numerologies:UL GF MCOT=Max. UL GF Burst+Reservation Overhead+PartialSubframe(s)+Short Time Gap+DL GFG Feedback[ms],Min. GF Transmission Cycle Period=Ceil(1.05*UL GF M COT/Alignment TimeUnit[ms])[ATUs],Alignment Time Unit(ATU) is a Slot(7 OSs NCP/6 OSs ECP),One-shotCCA duration=PIFS=25 μs, andShort Time Gap=SIFS=16 μs,

where UL GF MCOT is the maximum channel occupancy time for a mediumaccess opportunity, Max. UL GF Burst is the maximum GF UL burst length,Reservation Overhead is the reservation overhead discussed previouslywith reference to FIG. 5 , Short Time Gap is a short inter-frame spaceor an UL to DL switching gap, DL GFG Feedback is the duration of a DLGFG feedback message transmitted by a base station, Alignment Time Unitis the durations of an alignment time unit, e.g. a slot in this example,and Ceil( ) is the ceiling function.

In some embodiments, a QoS priority class is assigned to a GF ED for GFUL traffic based on the delay tolerance of the traffic and/or theoverall volume of traffic that is intended for GF UL transmission. Forexample, because an ED that is configured to align its GF transmissionstarting time to a common GF transmission cycle will be allowed toassess the unlicensed medium for UL transmission only every GFtransmission cycle period, in some embodiments:

A higher priority class (lower priority class index) featuring a shorterMin. GF transmission cycle period and UL MCOT may be assigned toaccommodate UL traffic that is less delay-tolerant so that medium accessopportunities to transmit UL traffic occur more frequently; and

A lower priority class (higher priority class index) featuring a longerMin. GF transmission cycle period and UL MCOT may be assigned toaccommodate a larger volume of UL traffic.

In the numerology examples shown in FIGS. 10A-10D and 11A-11D, thefollowing options are selected for illustrative purposes:

Minimum GF transmission cycle period is targeted for maximum mediumaccess opportunities,

Four different frame structure designs described earlier, i.e., framestructures A, B, C, and D shown in FIG. 5 ,

DL GFG Feedback duration=2 OSs,

Sub-band resource numerologies applicable to unlicensed carrierfrequency, e.g.:

FIGS. 10A-10D show example numerologies for the following fiveSCS+cyclic prefix combinations and a 5 GHz unlicensed carrier frequency:15 KHz SCS+NCP, 30 KHz SCS+NCP, 30 KHz SCS+ECP, 60 KHz SCS+NCP, 60 KHzSCS+ECP; and

FIGS. 11A-11D show example numerologies for the following five SCS+CPcombinations and a 60 GHz unlicensed carrier frequency: 240 KHz SCS+NCP,480 KHz SCS+NCP, 480 KHz SCS+ECP, 960 KHz SCS+NCP, 960 KHz SCS+ECP.

In the example access parameter sets shown in FIGS. 10A-10D and 11A-11Dthe GF transmission cycles are aligned to a slot ATU. For example, thelast column of the tables shown in FIGS. 10A-10D and 11A-11D express theminimum GF transmission cycle period in integer multiples of units ofLTE slots in accordance with the equations for Min. GF TransmissionCycle Period provided above. However, a GF transmission cycle period maybe aligned to a different alignment time unit, such as a mini-slot or asymbol in other embodiments.

The use of different numerologies can allow the coexistence of a diverseset of use cases having a wide range quality of service (QoS)requirements, such as different levels of latency or reliabilitytolerance, as well as different bandwidth or signaling overheadrequirements. In one example, the base station can signal to the ED anindex representing a selected numerology, or a single parameter (e.g.,subcarrier spacing) of the selected numerology. The signaling can bedone in a dynamic or a semi-static manner, for example in a controlchannel such as the physical downlink control channel (PDCCH) or indownlink control information (DCI). Based on this signaling, the ED maydetermine the parameters of the selected numerology from otherinformation, such as a look-up table of candidate numerologies stored inmemory.

Further GFG Configuration Information

As noted above, in some embodiments a group of EDs are configured toalign their GF transmission starting times for a given unlicensedspectrum sub-band to a DL GFG common time alignment signal. In suchembodiments, the configuration information sent to the GFG EDs mayfurther include information related to GF transmission timing, such asinformation indicating a one-shot CCA duration to be used (if differentfrom default, i.e., 25 μsec) and/or information indicating atransmission starting time. For example, the information indicating atransmission starting time may indicate that GF UL burst transmissionshould start on the next OS after a short time gap from the end of theDL signal (transmission of a reservation signal by individual GFG EDsmay be required) or after multiple OSs following the next OS(transmission during a partial sub-frame by individual GFG EDs isrequired) so that the start of GF UL burst transmission is aligned tothe start of the next sub-frame.

In some embodiments, a base station may provide GFG feedback via a DLGFG feedback message either separately or within the DL GFG common timealignment signal. In such embodiments, the configuration informationsent to a group of GF EDs configured to align their GF transmissionstarting times for a given unlicensed spectrum sub-band to a DL GFGcommon time alignment signal may further include information indicatinga Group Ack/Nack Index Shift n (if different from a default, e.g., n=1)to indicate which previous GF UL burst transmission a GFG Ack/Nackfeedback applies to, e.g., the immediately preceding GF UL bursttransmission (i.e. n=1), or the GF UL burst transmission before that(i.e. n=2), etc. A GF ED may search its pre-configured Ack/Nack fieldcorresponding to its UL transmission j within the GFG feedback messagethat may be transmitted separately but concurrently with, or as part of,the DL common time alignment signal j+n even if the GF ED does notintend to transmit a GF UL transmission in response to the DL commontime alignment signal j+n. Note that, in embodiments where the GroupAck/Nack Index Shift n is employed, each GF ED may maintain a record ofthe last n GF bursts it transmitted. The record contains the HARQprocess IDs/CBG IDs included in each GF burst. As an alternative way ofassociating the Ack/Nack feedback with corresponding GF transmissions,the associated HARQ process IDs/CBG IDs can be directly indicated in theDL GFG common feedback message either explicitly or implicitly.

As noted above, in some embodiments, a base station may be configured totransmit the GFG common time alignment signal on a periodic orsemi-periodic basis, i.e. transmit a periodic DL GFG common timealignment signal with a target GF cycle period following a successfulLBT procedure, which can facilitate UL transmission of periodic soundingreference signals (SRS) or periodic channel state information (CSI)feedback. In such embodiments, in addition to the information related toGF transmission timing, and possibly a Group Ack/Nack Index Shift n, thegroup-specific configuration information to configure the GFG EDs mayfurther include information related to periodicity of UL SRStransmission and/or periodicity of UL CSI feedback transmission. Forexample, the group-specific configuration information may furtherinclude information indicating that GF EDs should periodically transmitUL SRS every N_(srs) GFG common time alignment signals, where N_(srs) isan integer 1, and/or information indicating that GF EDs should transmitUL CSI feedback every N_(esi), GFG common time alignment signals, whereN_(esi); is an integer 1. It is noted that N_(srs) and/or N_(esi) can beconfigured differently for each of the GFG EDs such that, for instance,each configuration RRC signal carries to the GFG ED its respectivevalues of N_(srs) and/or N_(esi); in addition to the respectivereference times for individual GFG EDs to initiate each of the SRS andCSI transmission cycles based on the periodic/semi-periodic transmissionof the DL GFG common alignment signal. FIG. 12 is a timing diagramshowing an example of unlicensed spectrum access procedures by first andsecond GF UEs, GF UE 1 and GF UE 2, configured to align theirtransmission starting times based on a common GFG time alignment signalto access an unlicensed spectrum sub-band for grant-free uplinktransmission in accordance with an embodiment of the present disclosure.

As shown in FIG. 12 , following a successful CCA (e.g., an LBT CAT4CCA), a base station transmits a GFG time alignment message, GFGTrigger, on time-frequency resources of the unlicensed spectrumsub-band. The base station may transmit the GFG time alignment messageafter a self-deferral period or after transmitting a reservation signalso that its transmission is aligned to a particular ATU, e.g.,slot-aligned. GF UE 1 and GF UE 2 are part of the GFG to which the GFGtime alignment message pertains and are configured to align their GFtransmission times to the end of the GFG time alignment message, whichwill cause their CCAs to be synchronized. If the CCA (e.g. an LBT CAT 2CCA) performed by a GF UE is successful, then the GF UE may transmit aGF UL bursts within an UL MCOT following the successful CCA. In someembodiments, prior to transmitting a GF UL burst, a GF UE may transmit areservation signal (RSRV) and a partial subframe at the beginning of ULMCOT following a successful CCA so that the transmission of the GF ULburst is aligned to a particular ATU, e.g., slot-aligned. For example,in FIG. 12 , both GF UE 1 and GF UE 2 transmit a reservation signal anda partial subframe so that their respective GF UL bursts start at thenext ATU following their successful CCAs. This process is repeated atsome point after the end of the UL MCOT to again trigger potentialtime-aligned GF UL transmissions from the GFG.

As noted previously, in some embodiments the GFG time alignment messagemay include, or may be concurrent in the same common search space with,a GFG feedback message that provides, for example, GFG Ack/Nack feedbackrelated to previous GF UL burst(s). For example, as shown in the exampleembodiment illustrated in FIG. 12 , the third GFG Common Alignmentsignal (GFG CAS) includes a Group Ack/Nack Index Shift n=2, indicatingthat the GFG Ack/Nack feedback that is included as part of the third GFGCommon Alignment signal is related to TBs/CBGs that were transmitted inthe GF UL bursts that were aligned to the first GFG Common Alignmentsignal.

To provision for DL critical/periodic signals in the same unlicensedspectrum sub-band as the GF UL transmissions, such as DRS and paging,the base station may avoid transmitting the GFG Common Alignment signala guard period before the time that the base station intends to transmitthe DL critical/periodic signal(s), or the base station may indicate tothe GFG the maximum number of slots/subframes from the end of the CommonAlignment signal before which all GF UL bursts must end so that the DLcritical/periodic signal(s) can be transmitted between the end of thelast GF UL burst and before the next GFG Common Alignment signal.

As noted above, in some embodiments, a base station may be configured totransmit the GFG common time alignment signal on a periodic basis. FIG.13 is a timing diagram showing an example of unlicensed spectrum accessprocedures by first and second GF UEs, GF UE 1 and GF UE 2, configuredto align their transmission starting times based on a periodic commongrant-free group alignment message to access an unlicensed spectrumsub-band for grant-free uplink transmission in accordance with anembodiment of the present disclosure.

The unlicensed spectrum access procedures shown in FIG. 13 are similarto those shown in FIG. 12 , except that in the embodiment depicted inFIG. 13 , the base station transmits the GFG time alignment or triggersignal with a target GF period following a successful LBT procedure.Because of the target periodicity of this transmission, the LBTprocedure that the base station uses to access the unlicensed spectrumband may differ from that used in the embodiment depicted in FIG. 12 .For example, the LBT procedure performed by the base station for theembodiment shown in FIG. 13 may be a LBT CAT2 CCA. Although the basestation may target a particular periodicity for the transmission of theGFG Common Alignment signal, the base station may find the unlicensedspectrum to be unavailable/busy when it performs a CCA at a targetedperiod interval. An example of this is shown in FIG. 13 , where a CCAperformed by the base station fails (shown as Failed CCA in FIG. 13 ) ata targeted GF period interval. In order to try to minimize the deviationfrom the target periodicity, while also maintaining the alignment withthe intended ATU, the base station performs another CCA at the next ATUfollowing the Failed CCA, thus resulting in a semi-periodic transmissionof the GFG Common Alignment signal. In FIG. 13 , the CCA at the next ATUsucceeds and the base station then transmits a GFG Common Alignmentsignal. In some embodiments the base station may persistently performsubsequent CCAs at each of the subsequent ATUs until a subsequent CCAsucceeds within a fixed time window after which the medium accessattempt is deferred until the next targeted GF period interval.

In other embodiments, semi-periodicity may be realized if the CCA at atargeted GF period interval fails and the base station defers its mediumaccess attempt until the next targeted GF period interval.

It is noted that in the example embodiments shown in FIGS. 12 and 13 theunlicensed spectrum procedures performed by GF UE1 and GF UE2 areperformed for/on the same time-frequency resources of the unlicensedsub-band, but they have been shown separately in FIGS. 12 and 13 so asto illustrate their features more clearly.

FIGS. 14A and 14B are timing diagrams showing an example of twoasynchronous GF CCAs based on two asynchronous common grant-free groupalignment signals being used on two different unlicensed spectrumsub-bands in accordance with an embodiment of the present disclosure. Inparticular, FIG. 14A is a timing diagram showing an example ofunlicensed spectrum access procedures by first and second UEs, GF UE1and GF UE2, configured to align their transmission starting times basedon a first common grant-free group alignment signal to access a firstunlicensed spectrum sub-band, Unlicensed Sub-band 1, for grant-freeuplink transmission and FIG. 14B is a timing diagram showing an exampleof unlicensed spectrum access procedures by third and fourth UEs, GF UE3and GF UE4, configured to align their transmission starting times basedon a second common grant-free group alignment signal to access a secondunlicensed spectrum sub-band, Unlicensed Sub-band 2, for grant-freeuplink transmission.

It is noted that the unlicensed spectrum procedures performed by GF UE1and GF UE2 in Unlicensed Sub-band 1 are performed for/on the sametime-frequency resources of Unlicensed Sub-band 1, but they have beenshown separately in FIG. 14A so as to illustrate their features moreclearly. The unlicensed spectrum procedures performed by GF UE3 and GFUE4 in Unlicensed Sub-band 2 are also performed for/on the sametime-frequency resources of Unlicensed Sub-band 2, but are shownseparately in FIG. 14B for the same reason.

As noted above, and shown by way of example in FIGS. 14A and 14B, insome embodiments of the present disclosure a GF UE may transmit multiplerepetitions of a given TB within GF UL burst, and may do so for morethan one TB. For example, referring to FIG. 14A, it can be seen thatafter performing a successful LBT CAT 2 CCA, GF UE1 transmits fourrepetitions of two TBs, UE1 TB1 and UE1 TB2 within the subsequent GF ULburst.

As noted above, the GFGs of UEs share the time-frequency resources oftheir respective sub-bands, i.e., GF UE1 and GF UE2 share thetime-frequency resources of Unlicensed Sub-band 1 and GF UE3 and GF UE4share the time-frequency resources of Unlicensed Sub-band 2. However,that does not necessarily mean that the respective GF UL bursts within agiven sub-band overlap on all of the same time-frequency resourceswithin the sub-band. For example, the GF UL burst transmitted by GF UE1in FIG. 14A occupies a contiguous band of time-frequency resourceswithin Unlicensed Sub-band 1. In contrast, the GF UL burst transmittedby GF UE 2 in FIG. 14A occupies two frequency-separated bands oftime-frequency resources within Unlicensed Sub-band 1. As anotherexample, referring to FIG. 14B, it can be seen that GF UE3 and GF UE4each use frequency interlace hopping when transmitting their respectiveGF UL bursts. That is, GF UE3 and GF UE4 each use a respective sequenceof frequency interlaces to transmit their respective GF UL bursts withinUnlicensed Sub-band 2. In particular, GF UE3 uses a sequence offrequency interlaces that follows a pattern of Interlace 1, Interlace 2,and Interlace 1 over the course of three slots to transmit threerepetitions of one TB, UE3 TB1, while GF UE4 uses a sequence offrequency interlaces that follows a pattern of Interlace 3, Interlace 2,Interlace 3, and Interlace 1 over the course of four slots to transmittwo repetitions each of two TBs, UE4 TB1 and UE4 TB2 within UnlicensedSub-band 2.

As shown in FIGS. 14A and 14B, for each of the unlicensed spectrumsub-bands, Unlicensed Sub-band 1 and Unlicensed Sub-band 2, following asuccessful CCA (e.g., an LBT CAT4 CCA) on the respective sub-band thebase station transmits a respective GFG time alignment message, ontime-frequency resources of the sub-band. The main function of thecommon time alignment/trigger signal is to align the GFG transmissionstarting times. However, the common time alignment signal may includesome DCI content to address the GFG EDs. An enclosed GFG DCI message inthe GFG common time alignment signal may therefore contain one or moreof the feedbacks from base station discussed below.

GFG Feedback Contents and Transmission for GFG Common Time AlignmentSignal

For embodiments of the present disclosure in which a group of EDs areconfigured to align their GF transmission starting times to a commontime alignment signal that carries GFG DCI messages, the GFG DCI messagetransmitted as part of the GFG common time alignment/trigger signal maycontain one or more of the following as feedback from the base station:GFG Ack/Nack feedback; a MCS increase/decrease command for basestation-directed DCLLA or UL CSI feedback for ED-directed linkadaptation; a Transmit Power Control (TPC) increase/decrease command,e.g., if DCI format 3/3A is not employed separately; a SRS trigger; aCSI feedback trigger.

The GFG feedback message may include M ED-specific fields that includeinformation bits that provide the foregoing ED-specific feedback(s),where M is the number of GF EDs in the GFG.

A CRC encoder similar to the one shown in FIG. 8 may be used to form theGFG feedback message for GFGs configured for synchronous CCAs based on acommon CCA time alignment/trigger signal. For example, the GFG feedbackmessage may be formed by a CRC encoder that takes the bits of MED-specific fields and uses the GFG-RNTI to generate a CRC code that itappends to the M ED-specific fields to form the GFG feedback message.

The ED-specific GFG Ack/Nack feedback may include multiple bits (L),where L may be as large as the maximum number of TBs that can betransmitted during the maximum GF burst length, e.g., based on TBduration and the number of repetitions K. Alternatively, L may be aslarge as the maximum number of code block groups (CBGs) that can betransmitted during the maximum GF burst length.

The SRS trigger and the CSI feedback trigger may be included so as totrigger the GF EDs to transmit SRS and CSI feedback on the unlicensedspectrum band as part of their respective GF UL bursts following receiptof the common time alignment/trigger signal.

In some embodiments, the physical time-frequency resources used totransmit the GFG DCI message may be distributed in the frequency domainin order to comply with OCB regulatory requirements. For example, insome embodiments, the transmission resources may be distributed over asingle unlicensed channel of the GF sub-band, e.g., over a single 20 MHzunlicensed channel, according to a Interleaved Frequency DivisionMultiple Access (IFDMA) scheme with interleaved tones, a resource block(RB) interlace scheme, or as multi-clustered RBs. Alternatively, thenumber of unlicensed channels of the GF sub-band on which the GFG DCImessage are distributed may depend on the message size (M, L_(A/N),L_(TPC), L_(DCLLA)) and the mapping to control channel elements (CCEs).This number may be indicated to GF EDs in an RRC signal, for example.

FIG. 15 is a flow diagram of example operations 500 in an ED inaccordance with an embodiment of the present disclosure.

In block 502, the ED receives GF resource configuration information froma base station to configure the ED for GF uplink transmission inunlicensed spectrum, the GF resource configuration informationcomprising GF ED group-specific resource configuration informationindicating GF ED group-specific T/F resources of the unlicensed spectrumfor GF uplink transmission.

Optionally, in block 504, the ED performs a CCA in the unlicensedspectrum in accordance with the GF resource configuration information.In some embodiments, an ED does not perform a CCA if its GF uplinktransmission starts within a time gap permitted by regulation, e.g.,within 16 μs of the end of a DCI trigger transmitted by the basestation, as discussed previously.

In block 506, the ED transmits a GF uplink transmission over theunlicensed spectrum in accordance with the GF resource configurationinformation. For example, the ED's GF uplink transmission may be alignedto the GF uplink transmissions of one or more other GF EDs within thesame GF ED group, as discussed previously.

Optionally, in block 508, the ED monitors for a GF feedback message fromthe base station. For example, the ED may monitor for a multi-castgroup-specific GFG feedback message, as discussed previously.

The ED may then return to block 506 to transmit another GF uplinktransmission in accordance with the GF resource configurationinformation that it received from the base station.

The example operations 500 are illustrative of an example embodiment.Various ways to perform the illustrated operations, as well as examplesof other operations that may be performed, are described herein. Furthervariations may be or become apparent.

FIG. 16 is a flow diagram of examples operations 600 in a base stationin accordance with an embodiment of the present disclosure.

In block 602, the base station transmits grant-free (GF) resourceconfiguration information to configure one or more electronic devices(EDs) for GF uplink transmission in unlicensed spectrum, the GF resourceconfiguration information comprising GF ED group-specific resourceconfiguration information indicating GF ED group-specific time-frequencyresources of the unlicensed spectrum for GF uplink transmission.

In block 606, the base station receives a grant-free uplink transmissionon the GF ED group-specific T/F resources of the unlicensed spectrumfrom at least one of the EDs in the group in accordance with the GFresource configuration information. For example, the GF uplinktransmissions may be aligned to a common GF transmission cycle definedby a common GF transmission cycle reference start time and a common GFtransmission cycle period that are provided as part of the GF EDgroup-specific resource configuration information, as discussedpreviously.

Optionally, in block 606, the base station transmits a GF feedbackmessage that includes GF feedback for at least one of the one or moreEDs in the group. For example, the base station may multi-cast agroup-specific GFG feedback message, as discussed previously.

The base station may then return to block 504 to receive further GFuplink transmissions from GF EDs in the group in accordance with the GFresource configuration information that it provided.

The example operations 600 are illustrative of an example embodiment.Various ways to perform the illustrated operations, as well as examplesof other operations that may be performed, are described herein. Furthervariations may be or become apparent.

FIGS. 17A and 17B illustrate example devices that may implement themethods and teachings according to this disclosure. In particular, FIG.17A illustrates an example ED 110, and FIG. 17B illustrates an examplebase station 1370. These components could be used in the communicationsystem 100 or in any other suitable system.

As shown in FIG. 17A, the ED 110 includes at least one processing unit1400. The processing unit 1400 implements various processing operationsof the ED 1310. For example, the processing unit 1400 could performsignal coding, data processing, power control, input/output processing,or any other functionality enabling the ED 1310 to operate in thecommunication system 100. The processing unit 1400 may also beconfigured to implement some or all of the functionality and/orembodiments described in more detail above. Each processing unit 200includes any suitable processing or computing device configured toperform one or more operations. Each processing unit 1400 could, forexample, include a microprocessor, microcontroller, digital signalprocessor, field programmable gate array, or application specificintegrated circuit.

The ED 1310 also includes at least one transceiver 1402. The transceiver1402 is configured to modulate data or other content for transmission byat least one antenna or Network Interface Controller (NIC) 1404. Thetransceiver 1402 is also configured to demodulate data or other contentreceived by the at least one antenna 1404. Each transceiver 1402includes any suitable structure for generating signals for wireless orwired transmission and/or processing signals received wirelessly or bywire. Each antenna 1404 includes any suitable structure for transmittingand/or receiving wireless or wired signals. One or multiple transceivers1402 could be used in the ED 1310. One or multiple antennas 1404 couldbe used in the ED 1310. Although shown as a single functional unit, atransceiver 1402 could also be implemented using at least onetransmitter and at least one separate receiver.

The ED 1310 further includes one or more input/output devices 1406 orinterfaces (such as a wired interface to the internet 150). Theinput/output devices 1406 permit interaction with a user or otherdevices in the network. Each input/output device 1406 includes anysuitable structure for providing information to or receiving informationfrom a user, such as a speaker, microphone, keypad, keyboard, display,or touch screen, including network interface communications.

In addition, the ED 1310 includes at least one memory 1408. The memory1408 stores instructions and data used, generated, or collected by theED 1310. For example, the memory 1408 could store software instructionsor modules configured to implement some or all of the functionalityand/or embodiments described above and that are executed by theprocessing unit(s) 1400. Each memory 1408 includes any suitable volatileand/or non-volatile storage and retrieval device(s). Any suitable typeof memory may be used, such as random access memory (RAM), read onlymemory (ROM), hard disk, optical disc, subscriber identity module (SIM)card, memory stick, secure digital (SD) memory card, and the like.

As shown in FIG. 17B, the base station 1370 includes at least oneprocessing unit 1450, at least one transmitter 1452, at least onereceiver 1454, one or more antennas 1456, at least one memory 1458, andone or more input/output devices or interfaces 1466. A transceiver, notshown, may be used instead of the transmitter 1452 and receiver 1454. Ascheduler 1453 may be coupled to the processing unit 1450. The scheduler1453 may be included within or operated separately from the base station1370. The processing unit 1450 implements various processing operationsof the base station 1370, such as signal coding, data processing, powercontrol, input/output processing, or any other functionality. Theprocessing unit 1450 can also be configured to implement some or all ofthe functionality and/or embodiments described in more detail above.Each processing unit 1450 includes any suitable processing or computingdevice configured to perform one or more operations. Each processingunit 1450 could, for example, include a microprocessor, microcontroller,digital signal processor, field programmable gate array, or applicationspecific integrated circuit.

Each transmitter 1452 includes any suitable structure for generatingsignals for wireless or wired transmission to one or more EDs or otherdevices. Each receiver 1454 includes any suitable structure forprocessing signals received wirelessly or by wire from one or more EDsor other devices. Although shown as separate components, at least onetransmitter 1452 and at least one receiver 1454 could be combined into atransceiver. Each antenna 1456 includes any suitable structure fortransmitting and/or receiving wireless or wired signals. Although acommon antenna 1456 is shown here as being coupled to both thetransmitter 1452 and the receiver 1454, one or more antennas 1456 couldbe coupled to the transmitter(s) 1452, and one or more separate antennas1456 could be coupled to the receiver(s) 1454. Each memory 1458 includesany suitable volatile and/or non-volatile storage and retrievaldevice(s) such as those described above in connection to the ED 1310.The memory 1458 stores instructions and data used, generated, orcollected by the base station 1370. For example, the memory 1458 couldstore software instructions or modules configured to implement some orall of the functionality and/or embodiments described above and that areexecuted by the processing unit(s) 1450.

Each input/output device 1466 permits interaction with a user or otherdevices in the network. Each input/output device 1466 includes anysuitable structure for providing information to or receiving/providinginformation from a user, including network interface communications.

Referring now to FIG. 18A, shown is an example simplified block diagramof part of a transmitter that can be used to perform channelization asdescribed above. In this example, there are L supported numerologies,where L>2.

For each numerology, there is a respective transmit chain 1500, 1502.FIG. 18A shows simplified functionality for the first and L^(th)numerology; the functionality for other numerologies would be similar.Also shown in FIG. 18B is simplified functionality for a receive chain1503 for a receiver operating using the first numerology.

The transmit chain 1500 for the first numerology includes a modulator1510, subcarrier mapping and grouping block 1511, IFFT 1512 withsubcarrier spacing SC₁, parallel to serial and cyclic prefix insertion1514, and spectrum shaping filter 1516. In operation, modulator 1510receives ED data (more generally, ED content containing data and/orsignalling) for K₁ EDs, where K₁>=1. The data may be received from theoutput of an encoder. The modulator 1510 maps the ED data for each ofthe K₁ EDs to a respective stream of constellation symbols (e.g., PSK,QAM, OQAM) and outputs this at 1520. The number of ED bits per symboldepends on the particular constellation employed by the modulator 1510.In the example of 2^(N) quadrature amplitude modulation (QAM), N bitsfrom for each ED are mapped to a respective QAM symbol.

Optionally, for example in SC-FDMA embodiments used for uplinkcommunication, the output 1520 is received by a discrete Fouriertransform (DFT) 1526. The output of the DFT is shown at 1521. Otherembodiments, such as OFDM embodiments, do not include the DFT 1526, inwhich case the output 1520 is passed directly to 1521.

For each OFDM symbol period, the subcarrier mapping and grouping block1511 groups and maps the input 1521 to the inputs of the IFFT 1512 at1522. The grouping and mapping is performed based on schedulerinformation, which in turn is based on channelization and resource blockassignment, in accordance with a defined resource block definition andallocation for the content of the K₁ EDs being processed in transmitchain 1500. P is the size of the IFFT 1512. Not all of the inputs arenecessarily used for each OFDM symbol period. The IFFT 1512 receives anumber of symbols less than P, and outputs P time domain samples at1524. Following this, in some implementations, parallel to serialconversion is performed and a cyclic prefix is added in block 1514. Thespectrum shaping filter 1516 applies a filter f₁(n) which limits thespectrum at the output of the transmit chain 1500 to preventinterference with the outputs of other transmit chains such as transmitchain 1502. In some embodiments, the spectrum shaping filter 1516 alsoperforms shifting of each sub-band to its assigned frequency location.In other embodiments, a separate module (not shown) performs theshifting of each sub-band to its assigned frequency location.

The functionality of the other transmit chains, such as transmit chain1502 is similar. The outputs of all of the transmit chains are combinedin a combiner 1504 before transmission on the channel. In an alternativeembodiment, the outputs of only a subset of the transmit chains arecombined together for transmission on a single channel, and the outputsof the remaining transmit chains are transmitted on one or more otherchannels. This may be the case, for example, if RAN slicing is beingused.

Although the apparatus of FIG. 18A is shown and described in referenceto a base station, a similar structure could be implemented in an ED. AnED could have multiple transmit chains corresponding to multiplenumerologies, or a single transmit chain. The transmissions of multipleEDs are combined over the air, and received together at the basestation.

FIG. 18B shows a simplified block diagram of a receive chain for a userequipment or other electronic device operating with the first numerologydepicted at 1503. In some embodiments, a given ED is permanentlyconfigured to operate with a particular numerology. In some embodiments,a given ED operates with a software-configurable numerology. In eithercase, flexible resource block definitions are supported by the ED. Thereceive chain 1503 includes spectrum shaping filter 1530, cyclic prefixdeletion and serial to parallel processing 1532, fast Fourier transform(FFT) 1534, subcarrier de-mapping 1536, optional inverse DFT (IDFT) 1537for use with embodiment transmit chains including a DFT 1526, andequalizer 1538. It is contemplated that the spectrum shaping filter 1530may be replaced by a windowing module, a spectrally contained waveformselection module, or any other suitable module for producing aspectrally contained waveform. Each element in the receive chainperforms corresponding reverse operations to those performed in thetransmit chain. The receive chain for an ED operating with anothernumerology would be similar.

It should be appreciated that one or more steps of the embodimentmethods provided herein may be performed by corresponding units ormodules. For example, a signal may be transmitted by a transmitting unitor a transmitting module. A signal may be received by a receiving unitor a receiving module. A signal may be processed by a processing unit ora processing module. The respective units/modules may be hardware,software, or a combination thereof. For instance, one or more of theunits/modules may be an integrated circuit, such as field programmablegate arrays (FPGAs) or application-specific integrated circuits (ASICs).It will be appreciated that where the modules are software, they may beretrieved by a processor, in whole or part as needed, individually ortogether for processing, in single or multiple instances as required,and that the modules themselves may include instructions for furtherdeployment and instantiation.

Additional details regarding EDs and base stations are known to those ofskill in the art. As such, these details are omitted here for clarity.

In the preceding description, for purposes of explanation, numerousdetails are set forth in order to provide a thorough understanding ofthe embodiments. However, it will be apparent to one skilled in the artthat these specific details are not required. In other instances,well-known electrical structures and circuits are shown in block diagramform in order not to obscure the understanding. For example, specificdetails are not provided as to whether the embodiments described hereinare implemented as a software routine, hardware circuit, firmware, or acombination thereof.

Embodiments of the disclosure can be represented as a computer programproduct stored in a machine-readable medium (also referred to as acomputer-readable medium, a processor-readable medium, or a computerusable medium having a computer-readable program code embodied therein).The machine-readable medium can be any suitable tangible, non-transitorymedium, including magnetic, optical, or electrical storage mediumincluding a diskette, compact disk read only memory (CD-ROM), memorydevice (volatile or non-volatile), or similar storage mechanism. Themachine-readable medium can contain various sets of instructions, codesequences, configuration information, or other data, which, whenexecuted, cause a processor to perform steps in a method according to anembodiment of the disclosure. Those of ordinary skill in the art willappreciate that other instructions and operations necessary to implementthe described implementations can also be stored on the machine-readablemedium. The instructions stored on the machine-readable medium can beexecuted by a processor or other suitable processing device, and caninterface with circuitry to perform the described tasks.

EXAMPLE EMBODIMENTS

The following provides a non-limiting list of example embodiments of thepresent disclosure:

Example embodiment 1. A method for an electronic device (ED) in awireless communication network, the method comprising:

receiving, at an ED from a base station, grant-free (GF) resourceconfiguration information to configure the ED for GF uplink transmissionin unlicensed spectrum, the GF resource configuration informationcomprising GF ED group-specific resource configuration informationindicating GF ED group-specific time-frequency (T/F) resources of theunlicensed spectrum for GF uplink transmission; and

transmitting a grant-free uplink transmission over the unlicensedspectrum in accordance with the GF resource configuration information.

Example embodiment 2. The method of Example embodiment 1, furthercomprising monitoring for a GF feedback message from the base station.

Example embodiment 3. The method of Example embodiment 1 or 2, whereinthe GF resource configuration information further comprises a GF EDgroup-specific radio network temporary identifier (GFG-RNTI) for the EDto receive GFG common DCI messages from the base station.

Example embodiment 4. The method of Example embodiment 2 or 3, whereinthe GF feedback message from the base station is a GFG common feedbackmessage.

Example embodiment 5. The method of any of Example embodiments 1 to 4,further comprising performing a CCA in the unlicensed spectrum inaccordance with the GF resource configuration information, whereintransmitting a GF uplink transmission over the unlicensed spectrumcomprises starting the GF uplink transmission in accordance with the GFresource configuration information if the CCA is successful.

Example embodiment 6. The method of any of Example embodiments 1 to 5,wherein transmitting a GF uplink transmission over the unlicensedspectrum comprises starting the GF uplink transmission in alignment withthe GF uplink transmission of one or more EDs in the GF group.

Example embodiment 7. The method of any of Example embodiments 1 to 6,wherein the ED is part of more than one GF ED group, each GF ED groupincluding at least one ED.

Example embodiment 8. The method of Example embodiment 6 or 7, whereinthe GF uplink transmission of one ED or multiple ED of the group overthe unlicensed spectrum is aligned to:

a common GF transmission cycle;

a downlink (DL) group common time alignment signal;

a DL burst containing a Control Resource Set (CORESET) that includesED-specific and/or group common DCI triggers; or

a combination of two or more of the above.

Example embodiment 9. The method of any of Example embodiments 1 to 8,wherein the GF resource configuration information is received at leastpartially via a group-specific configuration message comprising the GFED group-specific resource configuration information to configure theEDs in the group for GF uplink transmission in the unlicensed spectrum.

Example embodiment 10. The method of any of Example embodiments 1 to 8,wherein the GF resource configuration information is received at leastpartially via an ED-specific configuration message.

Example embodiment 11. The method of any of Example embodiments 1 to 10,wherein the GF resource configuration information further comprisesinformation indicating a type of CCA to be used for accessing theunlicensed spectrum.

Example embodiment 12. The method of any of Example embodiments 1 to 11,further comprising transmitting, from the ED to the base station,information indicating at least one priority class associated with GFuplink traffic for the ED.

Example embodiment 13. The method of Example embodiment 12, wherein theinformation indicating at least one priority class is transmitted viauplink control information (UCI) or uplink radio resource control (ULRRC) signaling.

Example embodiment 14. The method of Example embodiment 12, wherein theinformation indicating at least one priority class is transmitted by theED as part of capability information that indicates the ED is aGF-capable device.

Example embodiment 15. The method of any of Example embodiments 1 to 14,wherein the GF resource configuration information is received entirelyvia radio resource control (RRC) signaling.

Example embodiment 16. The method of any of Example embodiments 1 to 15,wherein the GF resource configuration information is received in partvia RRC signaling and in part via downlink control information (DCI)that is part of an ED-specific or a group common trigger.

Example embodiment 17. The method of Example embodiment 5, wherein:

the GF resource configuration information further comprises informationindicating a reference start time and a GF transmission cycle period;and

transmitting a GF uplink transmission over the unlicensed spectrum inaccordance with the GF resource configuration information comprisesaligning the ED's GF uplink transmission in the T/F resources to thecommon GF transmission cycle defined by the common GF transmission cyclereference start time and the common GF transmission cycle period.

Example embodiment 18. The method of Example embodiment 5 or 17, whereinthe information indicating time-frequency resources of the unlicensedspectrum for grant-free uplink transmission comprises informationindicating one or more resource blocks (RBs) or a sequence of frequencyinterlaces within the time-frequency resources of the unlicensedspectrum for grant-free uplink transmission.

Example embodiment 19. The method of Example embodiment 17 or 18,wherein the GF resource configuration information further comprisesinformation indicating a plurality of potential GF occasions within a GFtransmission cycle at which the ED could potentially start a GF uplinktransmission.

Example embodiment 20. The method of Example embodiment 19, wherein theplurality of potential GF occasions includes a first occasion within theGF transmission cycle period, at least one subsequent occasion withinthe GF transmission cycle period being associated with a different setof GF parameters than the first occasion.

Example embodiment 21. The method of Example embodiment 20, wherein thedifferent sets of GF parameters associated with different occasionswithin the GF transmission cycle period differ in terms of one or moreof: transport format, number of repetitions, frequency interlacepattern, and frequency hopping pattern.

Example embodiment 22. The method of Example embodiment 20, furthercomprising:

in response to a CCA failing for the indicated GF occasion, performing aCCA for another potential GF occasion within the GF transmission cycleperiod; and

in response to the CCA for the other potential GF occasion succeeding,transmitting a grant-free uplink transmission over the unlicensedspectrum in accordance with the GF resource configuration informationand the respective set of GF parameters, within the GF transmissioncycle period.

Example embodiment 23. The method of Example embodiment 22, furthercomprising:

in response to a CCA for any GF occasion other than the last occasionsucceeding, transmitting a GF uplink transmission over the unlicensedspectrum and blanking a number of symbols at the end of that GF uplinktransmission to avoid potential CCA failures for neighboring EDsattempting to start a transmission at the immediately following GFoccasion; wherein the number of blanked symbols is the minimum numberthat accommodates the maximum duration of the CCA type configured forthe GF ED group.

Example embodiment 24. The method of any of Example embodiments 17 to23, wherein the reference start time is an absolute start time expressedas the index of an alignment time unit (ATU).

Example embodiment 25. The method of Example embodiment 24, wherein theATU index is the index of an Orthogonal Frequency Division Multiplexing(OFDM) symbol, the slot number, the subframe number or the system framenumber (SFN).

Example embodiment 26. The method of any of Example embodiments 17 to25, wherein the reference start time is a time offset relative to radioresource control (RRC) signaling carrying at least part of the GFresource configuration information.

Example embodiment 27. The method of any of Example embodiments 17 to25, wherein the reference start time is a time offset relative to

downlink control information (DCI) carrying at least part of the GFresource configuration information.

Example embodiment 28. The method of any of Example embodiments 17 to25, wherein the ED determines the reference start time based on the GFtransmission cycle period and time synchronization information.

Example embodiment 29. The method of Example embodiment 28, wherein thetime synchronization information is a current timer value of any one of:system frame number; subframe number; and slot number.

Example embodiment 30. The method of Example embodiment 29, wherein theGF ED sets the reference start time to Current Timer if Current Timersatisfies the formulae,Current Timer mod GF Cycle Period=q,

where Current Timer is the current timer value, GF Cycle Period and qare expressed as integer numbers of the same time unit as Current Timer,and q=0, 1, . . . , GF Cycle Period-1 is a configurable constant offsetthat is provided as part of the GF resource configuration information.

Example embodiment 31. The method of Example embodiment 30, wherein theconfigurable constant offset, q, is a parameter specific to the GF EDgroup to which the GF ED belongs for the alignment of a group common GFtransmission cycle across the GF group EDs.

Example embodiment 32. The method of any of Example embodiments 1 to 31,wherein receiving the GF ED group-specific resource configurationinformation comprises receiving the GF ED group-specific resourceconfiguration information via at least one of: ED-specific RadioResource Control (RRC) signaling; and a group common Physical DownlinkControl Channel (PDCCH) using a grant-free ED group identifierassociated with the group of EDs to identify group common DownlinkControl Information (DCI) intended for the group of EDs.

Example embodiment 33. The method of any of Example embodiments 1 to 32,wherein the GF ED group-specific resource configuration informationfurther comprises an indication of one or more occupationalbandwidth-compliant (OCB-compliant) frequency hopping patterns to beused by one or more EDs in the group for grant-free uplink transmissionwithin the T/F resources.

Example embodiment 34. The method of Example embodiment 33, wherein oneor more of the OCB-compliant frequency hopping patterns comprises atleast one of:

a sequence of frequency interlaces within the T/F resources;

a sequence of unlicensed channels to occupy within the T/F resources;and

a combination of i) and ii).

Example embodiment 35. The method of Example embodiment 33 or 34,wherein the one or more OCB-compliant frequency hopping patterns have asequence length that depends on the number of GF repetitions pertransport block.

Example embodiment 36. The method of any of Example embodiments 33 to35, wherein the indication of the T/F resources for the group of EDs touse for grant-free uplink transmission comprises a common seed value forthe ED to use with a common random number generator to generate a groupcommon random index of an OCB-compliant frequency interlace orunlicensed channel.

Example embodiment 37. The method of any of Example embodiments 1 to 36,wherein the GF ED group-specific resource configuration informationfurther comprises an indication of an ED-specific field format for agrant-free group (GFG) common downlink control information (DCI)message.

Example embodiment 38. The method of Example embodiment 37, wherein theGFG common DCI message includes a field to solicit a GF uplinktransmission.

Example embodiment 39. The method of any of Example embodiments 1 to 39,wherein the ED receives, from the base station, a GFG configurationmessage that includes the GF ED group-specific resource configurationinformation after at least one group ED regains time synchronizationwith the base station.

Example embodiment 40. The method of any of Example embodiments 17 to31, wherein transmitting a GF uplink transmission over the unlicensedspectrum in accordance with the GF resource configuration informationcomprises aligning the ED's GF uplink transmission in the T/F resourcesto the common GF transmission cycle defined by the common GFtransmission cycle reference start time and the common GF transmissioncycle period.

Example embodiment 41. The method of Example embodiment 40, wherein theinformation indicating a common GF transmission cycle reference starttime comprises information indicating a timing offset from an end of thetransmission of a message containing the GF ED group-specific resourceconfiguration information.

Example embodiment 42. The method of Example embodiment 40 or 41,wherein:

the GF ED group-specific resource configuration information furthercomprises information indicating a grant-free frame structure to be usedby the group of EDs for grant-free uplink transmission in the unlicensedspectrum; and

transmitting a grant-free uplink transmission over the unlicensedspectrum comprises transmitting the grant-free uplink transmission inaccordance with the grant-free frame structure indicated in the GF EDgroup-specific resource configuration information.

Example embodiment 43. The method of Example embodiment 42, wherein:

the grant-free frame structure is one of a plurality of pre-determinedgrant-free frame structures that are each associated with a respectivegrant-free frame structure index value; and

the information indicating the grant-free frame structure includesinformation indicating the respective grant-free frame structure indexvalue associated with the grant-free frame structure.

Example embodiment 44. The method of any of Example embodiments 40 to43, wherein the GF ED group-specific resource configuration informationcomprise information indicating a priority class index value associatedwith grant-free uplink traffic for the GF ED group, the priority classindex value being one priority class index value of a hierarchy ofpriority class index values, each priority class index value in thehierarchy being associated with a respective GF transmission cycleperiod and a respective maximum grant-free uplink burst length.

Example embodiment 45. The method of Example embodiment 44, wherein, foreach of at least a subset of the priority class index values in thehierarchy, the respective GF transmission cycle period associated withthe priority class index value exceeds a respective maximum channeloccupancy time (MCOT) associated with the priority class index valuesuch that a respective minimum idle period between the end of therespective MCOT and the end of the respective GF transmission cycleperiod is at least 5% of the length of the respective MCOT, therespective MCOT encompassing at least the respective maximum grant-freeuplink burst length associated with the priority class index value.

Example embodiment 46. The method of Example embodiment 45, wherein foreach of the priority class index values in the hierarchy, the respectiveMCOT associated with the priority class index value encompasses at leastthe respective maximum grant-free uplink burst length, areserved/partial subframe duration and a short time gap.

Example embodiment 47. The method of Example embodiment 46, wherein foreach of the priority class index values in the hierarchy, the respectiveMCOT associated with the priority class index value further encompassesa length of a grant-free group (GFG) feedback message.

Example embodiment 48. The method of any of Example embodiments 40 to47, further comprising:

in at least one common GF transmission cycle, receiving, over the T/Fresources, a downlink transmission within a dynamic idle period betweenan end of a last grant-free uplink transmission in the common GFtransmission cycle and before a start time of the CCA for the nextcommon GF transmission cycle.

Example embodiment 49. The method of any of Example embodiments 40 to47, further comprising:

in at least one common GF transmission cycle, receiving a schedulinggrant for a grant-based uplink transmission in another set of T/Fresources, wherein the scheduling grant is received within a dynamicidle period between an end of a last grant-free uplink transmission inthe common GF transmission cycle and before a start time of the CCA forthe next common GF transmission cycle; and

accessing the other set of T/F resources to transmit a grant-baseduplink in accordance with the received scheduling grant.

Example embodiment 50. The method of Example embodiment 49, wherein thescheduling grant includes information indicating the other set of T/Fresources in which the grant-based uplink transmission is to be made andinformation indicating a CCA type to be used to access the other set ofT/F resources for grant-based uplink transmission.

Example embodiment 51. The method of any of Example embodiments 1 to 16,further comprising:

receiving, over the unlicensed spectrum resources, a multi-castgrant-free group (GFG) common time-alignment signal for the group ofEDs; and

timing the ED's group-aligned GF transmission in the unlicensed spectrumresources based on the GFG common time-alignment signal.

Example embodiment 52. The method of Example embodiment 51, whereinreceiving the multi-cast GFG common time-alignment signal comprisessearching for the multi-cast GFG common time-alignment signal in acommon time-frequency search space according to a target GF cycleperiodicity.

Example embodiment 53. The method of Example embodiment 51 or 52,wherein the GFG common time-alignment signal comprises a GFG feedbackmessage that includes, for the ED, an ED-specific information field thatincludes Ack/Nack feedback related to one or more transport blockstransmitted by the ED within an earlier grant-free uplink transmission.

Example embodiment 54. The method of any of Example embodiments 1 to 53,wherein transmitting a grant-free uplink transmission over theunlicensed spectrum T/F resources comprises transmitting uplink controlsignaling at the start of the grant-free uplink transmission.

Example embodiment 55. The method of any of Example embodiments 1 to 54,further comprising:

receiving a multi-cast group-specific grant-free group (GFG) feedbackmessage on T/F resources of the unlicensed spectrum.

Example embodiment 56. The method of Example embodiment 55, whereinreceiving a multi-cast group-specific grant-free group (GFG) feedbackmessage comprises receiving the multi-cast GFG feedback message after alast grant-free uplink burst from one of the EDs in the group ends andwithin a maximum channel occupancy time (MCOT).

Example embodiment 57. The method of Example embodiment 56, wherein theGFG feedback message comprises, for each of one or more EDs in thegroup, an information field that includes Acknowledgement/NegativeAcknowledgement (Ack/Nack) feedback related to one or more transportblocks transmitted by the ED within a grant-free uplink burst during theMCOT in which the GFG Ack/Nack feedback message is multi-cast and/orrelated to one or more transport blocks transmitted by the ED withinprevious grant-free uplink bursts.

Example embodiment 58. The method of Example embodiment 55, whereinreceiving the multi-cast GFG feedback message comprises receiving themulti-cast GFG feedback message as part of a GFG common time-alignmentmessage, the GFG feedback message comprising, for each of one or moreEDs in the group, an information field that includes Ack/Nack feedbackrelated to one or more transport blocks transmitted by the ED within oneor more most recent grant-free uplink bursts preceding the GFG Ack/Nackfeedback message.

Example embodiment 59. The method of Example embodiment 55, whereinreceiving the multi-cast GFG feedback message comprises receiving themulti-cast GFG feedback message as part of a GFG common time-alignmentmessage, the GFG feedback message comprising:

an information field that includes Ack/Nack feedback related to one ormore transport blocks transmitted by the ED within a grant-free uplinkburst preceding the GFG Ack/Nack feedback message; and

a Group Ack/Nack Index Shift to indicate which previous grant-freeuplink burst the Ack/Nack feedback applies to.

Example embodiment 60. The method of any of Example embodiments 1 to 59,further comprising:

transmitting, on time-frequency resources of the unlicensed spectrumband, an indication to a base station that the ED will be using amodulation and coding scheme (MCS) for a grant-free uplink transmissionthat differs from a pre-configured MCS, wherein transmitting agrant-free uplink transmission over the unlicensed spectrum comprisestransmitting the grant-free uplink transmission using the indicated MCS.

Example embodiment 61. The method of Example embodiment 60, whereintransmitting the indication that the ED will be using a MCS that differsfrom a pre-configured MCS comprises transmitting the indication via anyone of:

a physical uplink control channel (PUCCH) carrying uplink controlinformation (UCI) at the beginning of the grant-free uplinktransmission;

a front-loaded pilot or demodulation reference signal (DMRS); and

uplink radio resource configuration (RRC) signaling transmitted by theED using the pre-configured MCS before starting transmission of thegrant-free uplink transmission using the MCS that differs from thepre-configured MCS.

Example embodiment 62. The method of any of Example embodiments 1 to 16,further comprising:

receiving, over the unlicensed spectrum resources, a downlink burst fromthe base station containing a control resource set (CORESET) thatincludes an ED-specific downlink control information (DCI) trigger forthe ED; and

timing the ED's group-aligned GF transmission in the unlicensed spectrumresources based on the downlink burst.

Example embodiment 63. The method of any of Example embodiments 17 to31, further comprising:

receiving, over the unlicensed spectrum resources, a downlink burst fromthe base station containing a control resource set (CORESET) thatincludes an ED-specific downlink control information (DCI) trigger forthe ED,

wherein at least part of the GF resource configuration information isreceived via the ED-specific downlink DCI trigger for the ED.

Example embodiment 64. The method of any one of Example embodiments 51to 53, further comprising:

receiving, over the unlicensed spectrum resources, a downlink burst fromthe base station containing a control resource set (CORESET) thatincludes an ED-specific downlink control information (DCI) trigger forthe ED,

wherein at least part of the GF resource configuration information isreceived via the ED-specific downlink DCI trigger for the ED.

Example embodiment 65. An electronic device (ED) comprising:

a memory storage comprising instructions; and

one or more processors in communication with the memory storage, whereinthe one or more processors execute the instructions to:

configure the ED for grant-free (GF) uplink transmission in unlicensedspectrum in accordance with GF resource configuration informationreceived from a base station, the GF resource configuration informationcomprising GF ED group-specific resource configuration informationindicating GF ED group-specific time-frequency (T/F) resources of theunlicensed spectrum for GF uplink transmission; and

transmit a grant-free uplink transmission over the unlicensed spectrumin accordance with the GF resource configuration information.

Example embodiment 66. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to monitor for a GF feedbackmessage from the base station.

Example embodiment 67. The ED of Example embodiment 65, wherein the GFresource configuration information further comprises a GF EDgroup-specific radio network temporary identifier (GFG-RNTI) for the EDto receive GFG common DCI messages from the base station.

Example embodiment 68. The ED of Example embodiment 66, wherein the GFfeedback message from the base station is a GFG common feedback message.

Example embodiment 69. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to:

perform a CCA in the unlicensed spectrum in accordance with the GFresource configuration information; and

start the GF uplink transmission in accordance with the GF resourceconfiguration information if the CCA is successful.

Example embodiment 70. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to start the GF uplinktransmission in alignment with the GF uplink transmission of one or moreEDs in the GF group.

Example embodiment 71. The ED of Example embodiment 65, wherein the EDis part of more than one GF ED group, each GF ED group including atleast one ED.

Example embodiment 72. The ED of Example embodiment 70, wherein the GFuplink transmission of one ED or multiple ED of the group over theunlicensed spectrum is aligned to:

a common GF transmission cycle;

a downlink (DL) group common time alignment signal;

a DL burst containing a Control Resource Set (CORESET) that includesED-specific and/or group common DCI triggers; or

a combination of two or more of the above.

Example embodiment 73. The ED of Example embodiment 65, wherein the GFresource configuration information is received at least partially via agroup-specific configuration message comprising the GF ED group-specificresource configuration information to configure the EDs in the group forGF uplink transmission in the unlicensed spectrum.

Example embodiment 74. The ED of Example embodiment 65, wherein the GFresource configuration information is received at least partially via anED-specific configuration message.

Example embodiment 75. The ED of Example embodiment 69, wherein the GFresource configuration information further comprises informationindicating a type of CCA to be used for accessing the unlicensedspectrum.

Example embodiment 76. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to transmit information tothe base station indicating at least one priority class associated withGF uplink traffic for the ED.

Example embodiment 77. The ED of Example embodiment 76, wherein theinformation indicating at least one priority class is transmitted viauplink control information (UCI) or uplink radio resource control (ULRRC) signaling.

Example embodiment 78. The ED of Example embodiment 76, wherein theinformation indicating at least one priority class is transmitted by theED as part of capability information that indicates the ED is aGF-capable device.

Example embodiment 79. The ED of Example embodiment 65, wherein the GFresource configuration information is received entirely via radioresource control (RRC) signaling.

Example embodiment 80. The ED of Example embodiment 65, wherein the GFresource configuration information is received in part via RRC signalingand in part via downlink control information (DCI) that is part of anED-specific or a group common trigger.

Example embodiment 81. The ED of Example embodiment 69, wherein:

the GF resource configuration information further comprises informationindicating a reference start time and a GF transmission cycle period;and

the one or more processors execute the instructions to align the ED's GFuplink transmission in the T/F resources to the common GF transmissioncycle defined by the common GF transmission cycle reference start timeand the common GF transmission cycle period.

Example embodiment 82. The ED of Example embodiment 69, wherein theinformation indicating time-frequency resources of the unlicensedspectrum for grant-free uplink transmission comprises informationindicating one or more resource blocks (RBs) or a sequence of frequencyinterlaces within the time-frequency resources of the unlicensedspectrum for grant-free uplink transmission.

Example embodiment 83. The ED of Example embodiment 81, wherein the GFresource configuration information further comprises informationindicating a plurality of potential GF occasions within a GFtransmission cycle at which the ED could potentially start a GF uplinktransmission.

Example embodiment 84. The ED of Example embodiment 83, wherein theplurality of potential GF occasions includes a first occasion within theGF transmission cycle period, at least one subsequent occasion withinthe GF transmission cycle period being associated with a different setof GF parameters than the first occasion.

Example embodiment 85. The ED of Example embodiment 84, wherein thedifferent sets of GF parameters associated with different occasionswithin the GF transmission cycle period differ in terms of one or moreof: transport format, number of repetitions, frequency interlacepattern, and frequency hopping pattern.

Example embodiment 86. The ED of Example embodiment 83, wherein the oneor more processors execute the instructions to:

in response to a CCA failing for the indicated GF occasion, perform aCCA for another potential GF occasion within the GF transmission cycleperiod; and

in response to the CCA for the other potential GF occasion succeeding,transmit a grant-free uplink transmission over the unlicensed spectrumin accordance with the GF resource configuration information within theGF transmission cycle period.

Example embodiment 87. The ED of Example embodiment 81, wherein thereference start time is an absolute start time expressed as the index ofan alignment time unit (ATU).

Example embodiment 88. The ED of Example embodiment 87, wherein the ATUindex is the index of an Orthogonal Frequency Division Multiplexing(OFDM) symbol, the slot number, the subframe number or the system framenumber (SFN).

Example embodiment 89. The ED of Example embodiment 81, wherein thereference start time is a time offset relative to radio resource control(RRC) signaling carrying at least part of the GF resource configurationinformation.

Example embodiment 90. The ED of Example embodiment 81, wherein thereference start time is a time offset relative to downlink controlinformation (DCI) carrying at least part of the GF resourceconfiguration information.

Example embodiment 91. The ED of Example embodiment 81, wherein the oneor more processors execute the instructions to determine the referencestart time based on the GF transmission cycle period and timesynchronization information.

Example embodiment 92. The ED of Example embodiment 91, wherein the timesynchronization information is a current timer value of any one of:system frame number; subframe number; or slot number.

Example embodiment 93. The ED of Example embodiment 92, wherein the oneor more processors execute the instructions to set the reference starttime to Current Timer if Current Timer satisfies the formulae,Current Timer mod GF Cycle Period=q,

where Current Timer is the current timer value, GF Cycle Period and qare expressed as integer numbers of the same time unit as Current Timer,and q=0, 1, . . . , GF Cycle Period-1 is a configurable constant offsetthat is provided as part of the GF resource configuration information.

Example embodiment 94. The ED of Example embodiment 93, wherein theconfigurable constant offset, q, is a parameter specific to the GF EDgroup to which the GF ED belongs for the alignment of a group common GFtransmission cycle across the GF group EDs.

Example embodiment 95. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to receive the GF EDgroup-specific resource configuration information via at least one of:ED-specific Radio Resource Control (RRC) signaling; and a group commonPhysical Downlink Control Channel (PDCCH) using a grant-free ED groupidentifier associated with the group of EDs to identify group commonDownlink Control Information (DCI) intended for the group of EDs.

Example embodiment 96. The ED of Example embodiment 65, wherein

the GF ED group-specific resource configuration information furthercomprises an indication of one or more occupational bandwidth-compliant(OCB-compliant) frequency hopping patterns to be used by one or more EDsin the group for grant-free uplink transmission within the T/Fresources.

Example embodiment 97. The ED of Example embodiment 96, wherein one ormore of the OCB-compliant frequency hopping patterns comprises at leastone of:

a sequence of frequency interlaces within the T/F resources;

a sequence of unlicensed channels to occupy within the T/F resources;and

a combination of i) and ii).

Example embodiment 98. The ED of Example embodiment 96, wherein the oneor more OCB-compliant frequency hopping patterns have a sequence lengththat depends on the number of GF repetitions per transport block.

Example embodiment 99. The ED of Example embodiment 96, wherein:

the indication of the T/F resources for the group of EDs to use forgrant-free uplink transmission comprises a common seed value; and

the one or more processors execute the instructions to use the commonseed value with a common random number generator to generate a groupcommon random index of an OCB-compliant frequency interlace orunlicensed channel.

Example embodiment 100. The ED of Example embodiment 65, wherein the GFED group-specific resource configuration information further comprisesan indication of an ED-specific field format for a grant-free group(GFG) common downlink control information (DCI) message.

Example embodiment 101. The ED of Example embodiment 100, wherein theGFG common DCI message includes a field to solicit a GF uplinktransmission.

Example embodiment 102. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to receive, from the basestation, a GFG configuration message that includes the GF EDgroup-specific resource configuration information after the ED regainstime synchronization with the base station.

Example embodiment 103. The ED of Example embodiment 91, wherein the oneor more processors execute the instructions to align the ED's GF uplinktransmission in the T/F resources to the common GF transmission cycledefined by the common GF transmission cycle reference start time and thecommon GF transmission cycle period.

Example embodiment 104. The ED of Example embodiment 103, wherein theinformation indicating a common GF transmission cycle reference starttime comprises information indicating a timing offset from an end of thetransmission of a message containing the GF ED group-specific resourceconfiguration information.

Example embodiment 105. The ED of Example embodiment 103, wherein:

the GF ED group-specific resource configuration information furthercomprises information indicating a grant-free frame structure to be usedby the group of EDs for grant-free uplink transmission in the unlicensedspectrum; and

the one or more processors execute the instructions to transmit thegrant-free uplink transmission in accordance with the grant-free framestructure indicated in the GF ED group-specific resource configurationinformation.

Example embodiment 106. The ED of Example embodiment 105, wherein:

the grant-free frame structure is one of a plurality of pre-determinedgrant-free frame structures that are each associated with a respectivegrant-free frame structure index value; and

the information indicating the grant-free frame structure includesinformation indicating the respective grant-free frame structure indexvalue associated with the grant-free frame structure.

Example embodiment 107. The ED of Example embodiment 103, wherein the GFED group-specific resource configuration information compriseinformation indicating a priority class index value associated withgrant-free uplink traffic for the GF ED group, the priority class indexvalue being one priority class index value of a hierarchy of priorityclass index values, each priority class index value in the hierarchybeing associated with a respective GF transmission cycle period and arespective maximum grant-free uplink burst length.

Example embodiment 108. The ED of Example embodiment 107, wherein, foreach of at least a subset of the priority class index values in thehierarchy, the respective GF transmission cycle period associated withthe priority class index value exceeds a respective maximum channeloccupancy time (MCOT) associated with the priority class index valuesuch that a respective minimum idle period between the end of therespective MCOT and the end of the respective GF transmission cycleperiod is at least 5% of the length of the respective MCOT, therespective MCOT encompassing at least the respective maximum grant-freeuplink burst length associated with the priority class index value.

Example embodiment 109. The ED of Example embodiment 108, wherein foreach of the priority class index values in the hierarchy, the respectiveMCOT associated with the priority class index value encompasses at leastthe respective maximum grant-free uplink burst length, areserved/partial subframe duration and a short time gap.

Example embodiment 110. The ED of Example embodiment 109, wherein foreach of the priority class index values in the hierarchy, the respectiveMCOT associated with the priority class index value further encompassesa length of a grant-free group (GFG) feedback message.

Example embodiment 111. The ED of Example embodiment 103, wherein theone or more processors execute the instructions to:

in at least one common GF transmission cycle, receive, over the T/Fresources, a downlink transmission within a dynamic idle period betweenan end of a last grant-free uplink transmission in the common GFtransmission cycle and before a start time of the CCA for the nextcommon GF transmission cycle.

Example embodiment 112. The ED of Example embodiment 103, wherein theone or more processors execute the instructions to:

in at least one common GF transmission cycle, receive a scheduling grantfor a grant-based uplink transmission in another set of T/F resources,wherein the scheduling grant is received within a dynamic idle periodbetween an end of a last grant-free uplink transmission in the common GFtransmission cycle and before a start time of the CCA for the nextcommon GF transmission cycle; and

access the other set of T/F resources to transmit a grant-based uplinkin accordance with the received scheduling grant.

Example embodiment 113. The ED of Example embodiment 112, wherein thescheduling grant includes information indicating the other set of T/Fresources in which the grant-based uplink transmission is to be made andinformation indicating a CCA type to be used to access the other set ofT/F resources for grant-based uplink transmission.

Example embodiment 114. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to:

receive, over the unlicensed spectrum resources, a multi-cast grant-freegroup (GFG) common time-alignment signal for the group of EDs; and

time the ED's group-aligned GF transmission in the unlicensed spectrumresources based on the GFG common time-alignment signal.

Example embodiment 115. The ED of Example embodiment 114, wherein theone or more processors execute the instructions to search for themulti-cast GFG common time-alignment signal in a common time-frequencysearch space according to a target GF cycle periodicity.

Example embodiment 116. The ED of Example embodiment 114, wherein theGFG common time-alignment signal comprises a GFG feedback message thatincludes, for the ED, an ED-specific information field that includesAck/Nack feedback related to one or more transport blocks transmitted bythe ED within an earlier grant-free uplink transmission.

Example embodiment 117. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to transmit uplink controlsignaling at the start of the grant-free uplink transmission.

Example embodiment 118. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to:

receive a multi-cast group-specific grant-free group (GFG) feedbackmessage on T/F resources of the unlicensed spectrum.

Example embodiment 119. The ED of Example embodiment 118, wherein theone or more processors execute the instructions to receive themulti-cast GFG feedback message after a last grant-free uplink burstfrom one of the EDs in the group ends and within a maximum channeloccupancy time (MCOT).

Example embodiment 120. The ED of Example embodiment 119, wherein theGFG feedback message comprises, for each of one or more EDs in thegroup, an information field that includes Acknowledgement/NegativeAcknowledgement (Ack/Nack) feedback related to one or more transportblocks transmitted by the ED within a grant-free uplink burst during theMCOT in which the GFG Ack/Nack feedback message is multi-cast and/orrelated to one or more transport blocks transmitted by the ED withinprevious grant-free uplink bursts.

Example embodiment 121. The ED of Example embodiment 118, wherein theone or more processors execute the instructions to receive themulti-cast GFG feedback message as part of a GFG common time-alignmentmessage, the GFG feedback message comprising, for each of one or moreEDs in the group, an information field that includes Ack/Nack feedbackrelated to one or more transport blocks transmitted by the ED within oneor more most recent grant-free uplink bursts preceding the GFG Ack/Nackfeedback message.

Example embodiment 122. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to:

receive, over the unlicensed spectrum resources, a downlink burst fromthe base station containing a control resource set (CORESET) thatincludes an ED-specific downlink control information (DCI) trigger forthe ED; and

time the ED's group-aligned GF transmission in the unlicensed spectrumresources based on the downlink burst.

Example embodiment 123. The ED of Example embodiment 118, wherein theone or more processors execute the instructions to receive themulti-cast GFG feedback message as part of a GFG common time-alignmentmessage, the GFG feedback message comprising:

an information field that includes Ack/Nack feedback related to one ormore transport blocks transmitted by the ED within a grant-free uplinkburst preceding the GFG Ack/Nack feedback message; and

a Group Ack/Nack Index Shift to indicate which previous grant-freeuplink burst the Ack/Nack feedback applies to.

Example embodiment 124. The ED of Example embodiment 65, wherein the oneor more processors execute the instructions to:

transmit, on time-frequency resources of the unlicensed spectrum band,an indication to a base station that the ED will be using a modulationand coding scheme (MCS) for a grant-free uplink transmission thatdiffers from a pre-configured MCS; and

transmit the grant-free uplink transmission using the indicated MCS.

Example embodiment 125. The ED of Example embodiment 123, wherein theone or more processors execute the instructions to transmit theindication via any one of:

a physical uplink control channel (PUCCH) carrying uplink controlinformation (UCI) at the beginning of the grant-free uplinktransmission;

a front-loaded pilot or demodulation reference signal (DMRS); and

uplink radio resource configuration (RRC) signaling transmitted by theED using the pre-configured MCS before starting transmission of thegrant-free uplink transmission using the MCS that differs from thepre-configured MCS.

Example embodiment 126. A method for a base station in a wirelesscommunication network, the method comprising:

transmitting grant-free (GF) resource configuration information toconfigure one or more electronic devices (EDs) for GF uplinktransmission in unlicensed spectrum, the GF resource configurationinformation comprising GF ED group-specific resource configurationinformation indicating GF ED group-specific time-frequency resources ofthe unlicensed spectrum for GF uplink transmission.

Example embodiment 127. The method of Example embodiment 126, furthercomprising transmitting a GF feedback message that includes GF feedbackfor at least one of the one or more EDs.

Example embodiment 128. The method of Example embodiment 126 or 127,wherein the GF resource configuration information further comprises a GFED group-specific radio network temporary identifier (GFG-RNTI) for theone or more EDs to use to receive GFG common DCI messages from the basestation.

Example embodiment 129. The method of Example embodiment 127 or 128,wherein the GF feedback message from the base station is a GFG commonfeedback message.

Example embodiment 130. The method of any of Example embodiments 126 to129, wherein transmitting the GF resource configuration informationcomprises transmitting the GF resource configuration information atleast partially via a group-specific configuration message comprisingthe GF ED group-specific configuration information to configure the EDsin the group for GF uplink transmission in the unlicensed spectrum.

Example embodiment 131. The method any of Example embodiments 126 to130, wherein transmitting the GF resource configuration informationcomprises transmitting the GF resource configuration information atleast partially via an ED-specific configuration message.

Example embodiment 132. The method any of Example embodiments 126 to131, wherein the GF resource configuration information further comprisesinformation indicating a type of CCA to be used for accessing theunlicensed spectrum.

Example embodiment 133. The method any of Example embodiments 126 to132, further comprising receiving, from at least one of the one or moreEDs information indicating at least one priority class associated withGF uplink traffic for the ED.

Example embodiment 134. The method of Example embodiment 133, whereinthe information indicating at least one priority class is received viauplink control information (UCI) or uplink radio resource control (ULRRC) signaling.

Example embodiment 135. The method of Example embodiment 133, whereinthe information indicating at least one priority class is received fromthe ED as part of capability information that indicates the ED is aGF-capable device.

Example embodiment 136. The method of any of Example embodiments 126 to135, wherein transmitting the GF resource configuration informationcomprises transmitting the GF resource configuration informationentirely via radio resource control (RRC) signaling.

Example embodiment 137. The method of any of Example embodiments 126 to135, wherein transmitting the GF resource configuration informationcomprises:

transmitting the GF resource configuration information in part via RRCsignaling; and

transmitting the GF resource configuration information in part viadownlink control information (DCI) that is part of an ED-specific or agroup common trigger.

Example embodiment 138. The method of any of Example embodiments 126 to137, wherein the GF resource configuration information further comprisesinformation indicating a reference start time and a GF transmissioncycle period.

Example embodiment 139. The method of any of Example embodiments 126 to138, wherein the information indicating time-frequency resources of theunlicensed spectrum for grant-free uplink transmission comprisesinformation indicating one or more resource blocks (RBs) or a sequenceof frequency interlaces within the time-frequency resources of theunlicensed spectrum for grant-free uplink transmission.

Example embodiment 140. The method of Example embodiment 138, whereinthe GF resource configuration information further comprises informationindicating a plurality of potential GF occasions within a GFtransmission cycle at which the one or more EDs could potentially starta GF uplink transmission.

Example embodiment 141. The method of Example embodiment 140, whereinthe plurality of potential GF occasions includes a first occasion withinthe GF transmission cycle period, at least one subsequent occasionwithin the GF transmission cycle period being associated with adifferent set of GF parameters than the first occasion.

Example embodiment 142. The method of Example embodiment 141, whereinthe different sets of GF parameters associated with different occasionswithin the GF transmission cycle period differ in terms of one or moreof: transport format, number of repetitions, frequency interlacepattern, and frequency hopping pattern.

Example embodiment 143. The method of Example embodiment 140 or 141,further comprising:

for a given ED, in response to failing to detect a GF uplinktransmission from the ED for the indicated GF occasion, monitoring for aGF uplink transmission from the ED for another potential GF occasionwithin the GF transmission cycle period.

Example embodiment 144. The method of any of Example embodiments 138 to143, wherein the reference start time is an absolute start timeexpressed as the index of an alignment time unit (ATU).

Example embodiment 145. The method of Example embodiment 144, whereinthe ATU is the index of an Orthogonal Frequency Division Multiplexing(OFDM) symbol, the slot number, the subframe number or the system framenumber (SFN).

Example embodiment 146. The method of any of Example embodiments 138 to145, wherein the reference start time is a time offset relative to radioresource control (RRC) signaling carrying at least part of the GFresource configuration information.

Example embodiment 147. The method of any of Example embodiments 138 to145, wherein the reference start time is a time offset relative todownlink control information (DCI) carrying at least part of the GFresource configuration information.

Example embodiment 148. The method of any of Example embodiments 138 to145, wherein the reference start time is determined based on the GFtransmission cycle period and time synchronization information.

Example embodiment 149. The method of Example embodiment 148, whereinthe time synchronization information is a current timer value of any oneof: system frame number; subframe number; or slot number.

Example embodiment 150. The method of Example embodiment 149, whereinthe reference start time is set to Current Timer if Current Timersatisfies the formulae,Current Timer mod GF Cycle Period=q,

where Current Timer is the current timer value, GF Cycle Period and qare expressed as integer numbers of the same time unit as Current Timer,and q=0, 1, . . . , GF Cycle Period-1 is a configurable constant offsetthat is provided as part of the GF resource configuration information.

Example embodiment 151. The method of Example embodiment 150, whereinthe configurable constant offset, q, is a parameter specific to the GFED group to which the one or more GF EDs belong for the alignment of agroup common GF transmission cycle.

Example embodiment 152. The method of any of Example embodiments 126 to151, wherein transmitting the GF ED group-specific configurationinformation comprises transmitting the GF ED group-specificconfiguration information via at least one of: ED-specific RadioResource Control (RRC) signaling; and a group common Physical DownlinkControl Channel (PDCCH) using a grant-free ED group identifierassociated with the group of EDs to identify group common DownlinkControl Information (DCI) intended for the group of EDs.

Example embodiment 153. The method of any of Example embodiments 126 to152, wherein the GF ED group-specific resource configuration informationfurther comprises an indication of one or more occupationalbandwidth-compliant (OCB-compliant) frequency hopping patterns to beused by one or more EDs in the group for grant-free uplink transmissionwithin the T/F resources.

Example embodiment 154. The method of Example embodiment 153, whereinone or more of the OCB-compliant frequency hopping patterns comprises atleast one of:

a sequence of frequency interlaces within the T/F resources;

a sequence of unlicensed channels to occupy within the T/F resources;and

a combination of i) and ii).

Example embodiment 155. The method of Example embodiment 153 or 154,wherein the one or more OCB-compliant frequency hopping patterns have asequence length that depends on the number of GF repetitions pertransport block.

Example embodiment 156. The method of any of Example embodiments 153 to155, wherein the indication of the T/F resources for the group of EDs touse for grant-free uplink transmission comprises a common seed value forthe ED to use with a common random number generator to generate a groupcommon random index of an OCB-compliant frequency interlace orunlicensed channel.

Example embodiment 157. The method of any of Example embodiments 126 to156, wherein the GF ED group-specific resource configuration informationfurther comprises an indication of an ED-specific field format for agrant-free group (GFG) common downlink control information (DCI)message.

Example embodiment 158. The method of Example embodiment 157, whereinthe GFG common DCI message includes a field to solicit a GF uplinktransmission.

Example embodiment 159. The method of any of Example embodiments 126 to158, wherein the base station transmits a GFG configuration message thatincludes the GF ED group-specific resource configuration informationafter regaining time synchronization with at least one ED in the GF EDgroup.

Example embodiment 160. The method of any of Example embodiments 138 to151, further comprising receiving GF uplink transmissions over theunlicensed spectrum from the one or more EDs configured in accordancewith the GF resource configuration information, wherein the GF uplinktransmissions are aligned to a common GF transmission cycle defined bythe common GF transmission cycle reference start time and the common GFtransmission cycle period.

Example embodiment 161. The method of Example embodiment 160, whereinthe information indicating a common GF transmission cycle referencestart time comprises information indicating a timing offset from an endof the transmission of a message containing the GF ED group-specificresource configuration information.

Example embodiment 162. The method of Example embodiment 160 or 161,wherein the GF ED group-specific resource configuration informationfurther comprises:

information indicating a grant-free frame structure to be used by thegroup of EDs for grant-free uplink transmission in the unlicensedspectrum.

Example embodiment 163. The method of Example embodiment 162, wherein:

the grant-free frame structure is one of a plurality of pre-determinedgrant-free frame structures that are each associated with a respectivegrant-free frame structure index value; and

the information indicating the grant-free frame structure includesinformation indicating the respective grant-free frame structure indexvalue associated with the grant-free frame structure.

Example embodiment 164. The method of any of Example embodiments 160 to163, wherein the GF ED group-specific resource configuration informationcomprise information indicating a priority class index value associatedwith grant-free uplink traffic for the GF ED group, the priority classindex value being one priority class index value of a hierarchy ofpriority class index values, each priority class index value in thehierarchy being associated with a respective GF transmission cycleperiod and a respective maximum grant-free uplink burst length.

Example embodiment 165. The method of Example embodiment 164, wherein,for each of at least a subset of the priority class index values in thehierarchy, the respective GF transmission cycle period associated withthe priority class index value exceeds a respective maximum channeloccupancy time (MCOT) associated with the priority class index valuesuch that a respective minimum idle period between the end of therespective MCOT and the end of the respective GF transmission cycleperiod is at least 5% of the length of the respective MCOT, therespective MCOT encompassing at least the respective maximum grant-freeuplink burst length associated with the priority class index value.

Example embodiment 166. The method of Example embodiment 165, whereinfor each of the priority class index values in the hierarchy, therespective MCOT associated with the priority class index valueencompasses at least the respective maximum grant-free uplink burstlength, a reserved/partial subframe duration and a short time gap.

Example embodiment 167. The method of Example embodiment 166, whereinfor each of the priority class index values in the hierarchy, therespective MCOT associated with the priority class index value furtherencompasses a length of a grant-free group (GFG) feedback message.

Example embodiment 168. The method of any of Example embodiments 160 to167, further comprising:

for at least one common GF transmission cycle, scheduling at least oneED in the GF ED group for a grant-based uplink or downlink transmissionin the unlicensed spectrum, such that the grant-based uplink or downlinktransmission is scheduled within a dynamic idle period at the end of thecommon GF transmission cycle and has an ending time before a start timeof the CCA for the next common GF transmission cycle.

Example embodiment 169. The method of any of Example embodiments 160 to168, further comprising:

transmitting a scheduling grant to an ED within the GF ED group to grantthe ED T/F resources for grant-based uplink transmission within anotherset of T/F resources that does not overlap with the GF ED group-specificT/F resources for grant-free uplink transmission.

Example embodiment 170. The method of Example embodiment 169, whereinthe scheduling grant includes information indicating the other set ofT/F resources in which the grant-based uplink transmission is to be madeand a type of CCA to be used to access the other set of T/F resourcesfor grant-based uplink transmission.

Example embodiment 171. The method of Example embodiment 169 or 170,wherein the base station pre-emptively blanks a grant-based maximumchannel occupancy time (MCOT) to temporarily accommodate upcoming GFtransmissions from the GF ED group by instructing the GFG EDs to limittheir upcoming GF transmissions to an indicated length or to use apre-configured default length.

Example embodiment 172. The method of any of Example embodiments 126 to137, further comprising:

multi-casting a grant-free group (GFG) common time-alignment signal forthe group of EDs to use to time-align their potential GF uplinktransmissions, the GFG common time-alignment signal being multi-cast bythe base station to the group of EDs on T/F resources of the unlicensedspectrum sub-band following a successful listen-before talk (LBT) CCAindicating the T/F resources are available.

Example embodiment 173. The method of Example embodiment 172, whereinmulti-casting a GFG common time-alignment signal comprises periodicallymulti-casting the GFG common time-alignment signal according to a targetGF cycle periodicity.

Example embodiment 174. The method of Example embodiment 173, whereinperiodically multi-casting the GFG common time-alignment signalaccording to a target GF cycle periodicity comprises:

after a first LBT CCA for the T/F resources of the unlicensed spectrumfails in advance of a target GF cycle period, performing a second LBTCCA within the target GF cycle period at a start time in advance of asecond GFG common time-alignment point within the target GF cycleperiod; and

in response to the second LBT CCA succeeding, multi-casting the GFGcommon time-alignment signal to the group of EDs to use to time-aligntheir potential GF uplink transmissions in accordance with the secondGFG common time-alignment point within the target GF cycle period.

Example embodiment 175. The method of any of Example embodiments 172 to174, wherein the GFG common time-alignment signal comprises a GFGfeedback message that includes, for each of one or more EDs in thegroup, an information field that includes Ack/Nack feedback related toone or more transport blocks transmitted by the ED within an earliergrant-free uplink transmission.

Example embodiment 176. The method of any of Example embodiments 126 to175, further comprising:

receiving grant-free uplink transmissions on the GF ED group-specificT/F resources of the unlicensed spectrum from at least a subset of theEDs in the group, the grant-free uplink transmissions from different EDsin the group being at least partially separated on the GF EDgroup-specific T/F resources in terms of at least one of: a time domain,a frequency domain, a code domain, a power domain, and a space domain.

Example embodiment 177. The method of Example embodiment 176, whereintwo or more of the grant-free uplink transmissions from the GF ED groupat least partially collide on the GF ED group-specific T/F resources ofthe unlicensed spectrum.

Example embodiment 178. The method of Example embodiment 176 or 177,further comprising:

transmitting GF resource configuration information to configure one ormore EDs of a second GF ED group for GF uplink transmission in theunlicensed spectrum, the GF resource configuration information for thesecond GF ED group comprising GF ED group-specific resourceconfiguration information for the second GF ED group indicating a secondset of GF ED group-specific T/F resources for GF uplink transmission,

wherein the second set of GF ED group-specific T/F resources for thesecond GF ED group is non-overlapping with the first set of GF EDgroup-specific T/F resources for the first GF ED group to supportcontention-free GF uplink transmission across the two GF ED groups.

Example embodiment 179. The method of any of Example embodiments 176 to178, wherein receiving the grant-free uplink transmissions comprises,for at least one of the grant-free uplink transmissions, receivinguplink control signaling at the start of the grant-free uplinktransmission.

Example embodiment 180. The method of any of Example embodiments 126 to179, further comprising:

multi-casting a group-specific grant-free group (GFG) feedback messageto the group of EDs on T/F resources of the unlicensed spectrum.

Example embodiment 181. The method of Example embodiment 180, whereinthe group-specific GFG feedback message is multi-cast to the group ofEDs after a last grant-free uplink burst from one of the EDs in thegroup ends and within a maximum channel occupancy time (MCOT).

Example embodiment 182. The method of Example embodiment 181, whereinthe group-specific GFG feedback message comprises, for each of one ormore EDs in the group, an information field that includesAcknowledgement/Negative Acknowledgement (Ack/Nack) feedback related toone or more transport blocks transmitted by the ED within a grant-freeuplink burst during the MCOT in which the GFG Ack/Nack feedback messageis multi-cast and/or related to one or more transport blocks transmittedby the ED within previous grant-free uplink bursts.

Example embodiment 183. The method of any of Example embodiments 180 to182, wherein the group-specific GFG feedback message is multi-cast tothe group of EDs as part of a GFG common time-alignment message, the GFGfeedback message comprising, for each of one or more EDs in the group,an information field that includes Ack/Nack feedback related to one ormore transport blocks transmitted by the ED within one or more mostrecent grant-free uplink bursts preceding the GFG Ack/Nack feedbackmessage.

Example embodiment 184. The method of any of Example embodiments 180 to183, wherein the group-specific GFG feedback message comprises, for thegroup of EDs, at least one of: dynamic closed loop link adaptationcommands; and closed loop power control commands.

Example embodiment 185. The method of any of Example embodiments 126 to184, further comprising:

receiving, from an ED in the group of EDs on time-frequency resources ofthe unlicensed spectrum, an indication that the ED will be using amodulation and coding scheme (MCS) for a grant-free uplink transmissionthat differs from a pre-configured MCS; and

decoding one or more transport blocks received in the grant-free uplinktransmission from the ED based on the MCS that differs from thepre-configured MCS.

Example embodiment 186. The method of Example embodiment 185, whereinreceiving the indication that the ED will be using a MCS that differsfrom a pre-configured MCS comprises receiving the indication via any oneof:

a physical uplink control channel (PUCCH) carrying uplink controlinformation (UCI) at the beginning of the grant-free uplinktransmission;

a front-loaded pilot or demodulation reference signal (DMRS); and

uplink radio resource configuration (RRC) signaling transmitted by theED using the pre-configured MCS before starting transmission of thegrant-free uplink burst using the MCS that differs from thepre-configured MCS.

Example embodiment 187. A base station comprising:

a memory storage comprising instructions; and

one or more processors in communication with the memory storage, whereinthe one or more processors execute the instructions to:

transmit grant-free (GF) resource configuration information to configureone or more electronic devices (EDs) for GF uplink transmission inunlicensed spectrum, the GF resource configuration informationcomprising GF ED group-specific resource configuration informationindicating GF ED group-specific time-frequency resources of theunlicensed spectrum for GF uplink transmission.

Example embodiment 188. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to: transmita GF feedback message that includes GF feedback for at least one of theone or more EDs.

Example embodiment 189. The base station of Example embodiment 187,wherein the GF resource configuration information further comprises a GFED group-specific radio network temporary identifier (GFG-RNTI) for theone or more EDs to use to receive GFG common DCI messages from the basestation.

Example embodiment 190. The base station of Example embodiment 188,wherein the GF feedback message from the base station is a GFG commonfeedback message.

Example embodiment 191. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to transmitthe GF resource configuration information at least partially via agroup-specific configuration message comprising the GF ED group-specificconfiguration information to configure the EDs in the group for GFuplink transmission in the unlicensed spectrum.

Example embodiment 192. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to transmitthe GF resource configuration information at least partially via anED-specific configuration message.

Example embodiment 193. The base station of Example embodiment 187,wherein the GF resource configuration information further comprisesinformation indicating a type of CCA to be used for accessing theunlicensed spectrum.

Example embodiment 194. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to receive,from at least one of the one or more EDs information indicating at leastone priority class associated with GF uplink traffic for the ED.

Example embodiment 195. The base station of Example embodiment 194,wherein the information indicating at least one priority class isreceived via uplink control information (UCI) or uplink radio resourcecontrol (UL RRC) signaling.

Example embodiment 196. The base station of Example embodiment 194,wherein the information indicating at least one priority class isreceived from the ED as part of capability information that indicatesthe ED is a GF-capable device.

Example embodiment 197. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to transmitthe GF resource configuration information entirely via radio resourcecontrol (RRC) signaling.

Example embodiment 198. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to:

transmit the GF resource configuration information in part via RRCsignaling; and

transmit the GF resource configuration information in part via downlinkcontrol information (DCI) that is part of an ED-specific or a groupcommon trigger.

Example embodiment 199. The base station of Example embodiment 187,wherein the GF resource configuration information further comprisesinformation indicating a reference start time and a GF transmissioncycle period.

Example embodiment 200. The base station of Example embodiment 187,wherein the information indicating time-frequency resources of theunlicensed spectrum for grant-free uplink transmission comprisesinformation indicating one or more resource blocks (RBs) or a sequenceof frequency interlaces within the time-frequency resources of theunlicensed spectrum for grant-free uplink transmission.

Example embodiment 201. The base station of Example embodiment 199,wherein the GF resource configuration information further comprisesinformation indicating a plurality of potential GF occasions within a GFtransmission cycle at which the one or more EDs could potentially starta GF uplink transmission.

Example embodiment 202. The base station of Example embodiment 201,wherein the plurality of potential GF occasions includes a firstoccasion within the GF transmission cycle period, at least onesubsequent occasion within the GF transmission cycle period beingassociated with a different set of GF parameters than the firstoccasion.

Example embodiment 203. The base station of Example embodiment 202,wherein the different sets of GF parameters associated with differentoccasions within the GF transmission cycle period differ in terms of oneor more of: transport format, number of repetitions, frequency interlacepattern, and frequency hopping pattern.

Example embodiment 204. The base station of Example embodiment 201,wherein the one or more processors execute the instructions to:

for a given ED, in response to failing to detect a GF uplinktransmission from the ED for the indicated GF occasion, monitor for a GFuplink transmission from the ED for another potential GF occasion withinthe GF transmission cycle period.

Example embodiment 205. The base station of Example embodiment 199,wherein the reference start time is an absolute start time expressed asthe index of an alignment time unit (ATU).

Example embodiment 206. The base station of Example embodiment 205,wherein the ATU is the index of an Orthogonal Frequency DivisionMultiplexing (OFDM) symbol, the slot number, the subframe number or thesystem frame number (SFN).

Example embodiment 207. The base station of Example embodiment 199,wherein the reference start time is a time offset relative to radioresource control (RRC) signaling carrying at least part of the GFresource configuration information.

Example embodiment 208. The base station of Example embodiment 199,wherein the reference start time is a time offset relative to downlinkcontrol information (DCI) carrying at least part of the GF resourceconfiguration information.

Example embodiment 209. The base station of Example embodiment 199,wherein the reference start time is determined based on the GFtransmission cycle period and time synchronization information.

Example embodiment 210. The base station of Example embodiment 209,wherein the time synchronization information is a current timer value ofany one of: system frame number; subframe number; or slot number.

Example embodiment 211. The base station of Example embodiment 210,wherein the reference start time is set to Current Timer if CurrentTimer satisfies the formulae,Current Timer mod GF Cycle Period=q,

where Current Timer is the current timer value, GF Cycle Period and qare expressed as integer numbers of the same time unit as Current Timer,and q=0, 1, . . . , GF Cycle Period-1 is a configurable constant offsetthat is provided as part of the GF resource configuration information.

Example embodiment 212. The base station of Example embodiment 211,wherein the configurable constant offset, q, is a parameter specific tothe GF ED group to which the one or more GF EDs belong for the alignmentof a group common GF transmission cycle.

Example embodiment 213. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to transmitthe GF ED group-specific configuration information via at least one of:ED-specific Radio Resource Control (RRC) signaling; and a group commonPhysical Downlink Control Channel (PDCCH) using a grant-free ED groupidentifier associated with the group of EDs to identify group commonDownlink Control Information (DCI) intended for the group of EDs.

Example embodiment 214. The base station of Example embodiment 187,wherein the GF ED group-specific resource configuration informationfurther comprises an indication of one or more occupationalbandwidth-compliant (OCB-compliant) frequency hopping patterns to beused by one or more EDs in the group for grant-free uplink transmissionwithin the T/F resources.

Example embodiment 215. The base station of Example embodiment 214,wherein one or more of the OCB-compliant frequency hopping patternscomprises at least one of:

a sequence of frequency interlaces within the T/F resources;

a sequence of unlicensed channels to occupy within the T/F resources;and

a combination of i) and ii).

Example embodiment 216. The base station of Example embodiment 214,wherein the one or more OCB-compliant frequency hopping patterns have asequence length that depends on the number of GF repetitions pertransport block.

Example embodiment 217. The base station of Example embodiment 214,wherein the indication of the T/F resources for the group of EDs to usefor grant-free uplink transmission comprises a common seed value for theED to use with a common random number generator to generate a groupcommon random index of an OCB-compliant frequency interlace orunlicensed channel.

Example embodiment 218. The base station of Example embodiment 187,wherein the GF ED group-specific resource configuration informationfurther comprises an indication of an ED-specific field format for agrant-free group (GFG) common downlink control information (DCI)message.

Example embodiment 219. The base station of Example embodiment 208,wherein the GFG common DCI message includes a field to solicit a GFuplink transmission.

Example embodiment 220. The base station of Example embodiment 187,wherein the base station transmits a GFG configuration message thatincludes the GF ED group-specific resource configuration informationafter regaining time synchronization with at least one ED in the GF EDgroup.

Example embodiment 221. The base station of Example embodiment 199,wherein the one or more processors execute the instructions to receiveGF uplink transmissions over the unlicensed spectrum from the one ormore EDs configured in accordance with the GF resource configurationinformation, wherein the GF uplink transmissions are aligned to a commonGF transmission cycle defined by the common GF transmission cyclereference start time and the common GF transmission cycle period.

Example embodiment 222. The base station of Example embodiment 221,wherein the information indicating a common GF transmission cyclereference start time comprises information indicating a timing offsetfrom an end of the transmission of a message containing the GF EDgroup-specific resource configuration information.

Example embodiment 223. The base station of Example embodiment 221,wherein the GF ED group-specific resource configuration informationfurther comprises:

information indicating a grant-free frame structure to be used by thegroup of EDs for grant-free uplink transmission in the unlicensedspectrum.

Example embodiment 224. The base station of Example embodiment 223,wherein:

the grant-free frame structure is one of a plurality of pre-determinedgrant-free frame structures that are each associated with a respectivegrant-free frame structure index value; and

the information indicating the grant-free frame structure includesinformation indicating the respective grant-free frame structure indexvalue associated with the grant-free frame structure.

Example embodiment 225. The base station of Example embodiment 221,wherein the GF ED group-specific resource configuration informationcomprise information indicating a priority class index value associatedwith grant-free uplink traffic for the GF ED group, the priority classindex value being one priority class index value of a hierarchy ofpriority class index values, each priority class index value in thehierarchy being associated with a respective GF transmission cycleperiod and a respective maximum grant-free uplink burst length.

Example embodiment 226. The base station of Example embodiment 225,wherein, for each of at least a subset of the priority class indexvalues in the hierarchy, the respective GF transmission cycle periodassociated with the priority class index value exceeds a respectivemaximum channel occupancy time (MCOT) associated with the priority classindex value such that a respective minimum idle period between the endof the respective MCOT and the end of the respective GF transmissioncycle period is at least 5% of the length of the respective MCOT, therespective MCOT encompassing at least the respective maximum grant-freeuplink burst length associated with the priority class index value.

Example embodiment 227. The base station of Example embodiment 226,wherein for each of the priority class index values in the hierarchy,the respective MCOT associated with the priority class index valueencompasses at least the respective maximum grant-free uplink burstlength, a reserved/partial subframe duration and a short time gap.

Example embodiment 228. The base station of Example embodiment 227,wherein for each of the priority class index values in the hierarchy,the respective MCOT associated with the priority class index valuefurther encompasses a length of a grant-free group (GFG) feedbackmessage.

Example embodiment 229. The base station of Example embodiment 221,wherein the one or more processors execute the instructions to:

for at least one common GF transmission cycle, schedule at least one EDin the GF ED group for a grant-based uplink or downlink transmission inthe unlicensed spectrum, such that the grant-based uplink or downlinktransmission is scheduled within a dynamic idle period at the end of thecommon GF transmission cycle and has an ending time before a start timeof the CCA for the next common GF transmission cycle.

Example embodiment 230. The base station of Example embodiment 221,wherein the one or more processors execute the instructions to:

transmit a scheduling grant to an ED within the GF ED group to grant theED T/F resources for grant-based uplink transmission within another setof T/F resources that does not overlap with the GF ED group-specific T/Fresources for grant-free uplink transmission.

Example embodiment 231. The base station of Example embodiment 230,wherein the scheduling grant includes information indicating the otherset of T/F resources in which the grant-based uplink transmission is tobe made and a type of CCA to be used to access the other set of T/Fresources for grant-based uplink transmission.

Example embodiment 232. The base station of Example embodiment 230,wherein the base station pre-emptively blanks a grant-based maximumchannel occupancy time (MCOT) to temporarily accommodate upcoming GFtransmissions from the GF ED group by instructing the GFG EDs to limittheir upcoming GF transmissions to an indicated length or to use apre-configured default length.

Example embodiment 233. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to:

multi-cast a grant-free group (GFG) common time-alignment signal for thegroup of EDs to use to time-align their potential GF uplinktransmissions, the GFG common time-alignment signal being multi-cast bythe base station to the group of EDs on T/F resources of the unlicensedspectrum sub-band following a successful listen-before talk (LBT) CCAindicating the T/F resources are available.

Example embodiment 234. The base station of Example embodiment 233,wherein the one or more processors execute the instructions toperiodically multi-cast the GFG common time-alignment signal accordingto a target GF cycle periodicity.

Example embodiment 235. The base station of Example embodiment 234,wherein the one or more processors execute the instructions to:

after a first LBT CCA for the T/F resources of the unlicensed spectrumfails in advance of a target GF cycle period, perform a second LBT CCAwithin the target GF cycle period at a start time in advance of a secondGFG common time-alignment point within the target GF cycle period; and

in response to the second LBT CCA succeeding, multi-cast the GFG commontime-alignment signal to the group of EDs to use to time-align theirpotential GF uplink transmissions in accordance with the second GFGcommon time-alignment point within the target GF cycle period.

Example embodiment 236. The base station of Example embodiment 233,wherein the GFG common time-alignment signal comprises a GFG feedbackmessage that includes, for each of one or more EDs in the group, aninformation field that includes Ack/Nack feedback related to one or moretransport blocks transmitted by the ED within an earlier grant-freeuplink transmission.

Example embodiment 237. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to:

receive grant-free uplink transmissions on the GF ED group-specific T/Fresources of the unlicensed spectrum from at least a subset of the EDsin the group, the grant-free uplink transmissions from different EDs inthe group being at least partially separated on the GF ED group-specificT/F resources in terms of at least one of: a time domain, a frequencydomain, a code domain, a power domain, and a space domain.

Example embodiment 238. The base station of Example embodiment 237,wherein two or more of the grant-free uplink transmissions from the GFED group at least partially collide on the GF ED group-specific T/Fresources of the unlicensed spectrum.

Example embodiment 239. The base station of Example embodiment 237,wherein the one or more processors execute the instructions to:

transmit GF resource configuration information to configure one or moreEDs of a second GF ED group for GF uplink transmission in the unlicensedspectrum, the GF resource configuration information for the second GF EDgroup comprising GF ED group-specific resource configuration informationfor the second GF ED group indicating a second set of GF EDgroup-specific T/F resources for GF uplink transmission,

wherein the second set of GF ED group-specific T/F resources for thesecond GF ED group is non-overlapping with the first set of GF EDgroup-specific T/F resources for the first GF ED group to supportcontention-free GF uplink transmission across the two GF ED groups.

Example embodiment 240. The base station of Example embodiment 237,wherein the one or more processors execute the instructions to receiveuplink control signaling at the start of at least one of the grant-freeuplink transmissions.

Example embodiment 241. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to:

multi-cast a group-specific grant-free group (GFG) feedback message tothe group of EDs on T/F resources of the unlicensed spectrum.

Example embodiment 242. The base station of Example embodiment 241,wherein the group-specific GFG feedback message is multi-cast to thegroup of EDs after a last grant-free uplink burst from one of the EDs inthe group ends and within a maximum channel occupancy time (MCOT).

Example embodiment 243. The base station of Example embodiment 242,wherein the group-specific GFG feedback message comprises, for each ofone or more EDs in the group, an information field that includesAcknowledgement/Negative Acknowledgement (Ack/Nack) feedback related toone or more transport blocks transmitted by the ED within a grant-freeuplink burst during the MCOT in which the GFG Ack/Nack feedback messageis multi-cast and/or related to one or more transport blocks transmittedby the ED within previous grant-free uplink bursts.

Example embodiment 244. The base station of Example embodiment 241,wherein the group-specific GFG feedback message is multi-cast to thegroup of EDs as part of a GFG common time-alignment message, the GFGfeedback message comprising, for each of one or more EDs in the group,an information field that includes Ack/Nack feedback related to one ormore transport blocks transmitted by the ED within one or more mostrecent grant-free uplink bursts preceding the GFG Ack/Nack feedbackmessage.

Example embodiment 245. The base station of Example embodiment 236,wherein the group-specific GFG feedback message comprises, for the groupof EDs, at least one of: dynamic closed loop link adaptation commands;and closed loop power control commands.

Example embodiment 246. The base station of Example embodiment 187,wherein the one or more processors execute the instructions to:

receive, from an ED in the group of EDs on time-frequency resources ofthe unlicensed spectrum, an indication that the ED will be using amodulation and coding scheme (MCS) for a grant-free uplink transmissionthat differs from a pre-configured MCS; and

decode one or more transport blocks received in the grant-free uplinktransmission from the ED based on the MCS that differs from thepre-configured MCS.

Example embodiment 247. The base station of Example embodiment 246,wherein the one or more processors execute the instructions to receivethe indication via any one of:

a physical uplink control channel (PUCCH) carrying uplink controlinformation (UCI) at the beginning of the grant-free uplinktransmission;

a front-loaded pilot or demodulation reference signal (DMRS); and

uplink radio resource configuration (RRC) signaling transmitted by theED using the pre-configured MCS before starting transmission of thegrant-free uplink burst using the MCS that differs from thepre-configured MCS.

The contents of the drawings are intended solely for illustrativepurposes, and the present invention is in no way limited to theparticular example embodiments explicitly shown in the drawings anddescribed herein. For example, FIG. 1 is a block diagram of acommunication system in which embodiments may be implemented. Otherembodiments could be implemented in communication systems that includemore network elements than shown, or that have different topologies thanthe example shown. Similarly, the examples in the other figures are alsointended solely for illustrative purposes.

Other implementation details could also vary between differentembodiments. For example, some of the examples above refer to NR and LTEterminology. However, the embodiments disclosed herein are not in anyway limited to NR or LTE systems.

In addition, although described primarily in the context of methods andsystems, other implementations are also contemplated, as instructionsstored on a non-transitory processor-readable medium, for example. Theinstructions, when executed by one or more processors, cause the one ormore processors to perform a method.

The above-described embodiments are intended to be examples only.Alterations, modifications and variations can be effected to theparticular embodiments by those of skill in the art. The scope of theclaims should not be limited by the particular embodiments set forthherein, but should be construed in a manner consistent with thespecification as a whole.

The invention claimed is:
 1. A method comprising: receiving, by anelectronic device (ED) from a base station, configuration information,the configuration information indicating at least a transmission cycleperiod and an offset parameter for semi-static periodic access of atleast one channel of an unlicensed spectrum; determining, by the ED, areference start time for the semi-static periodic access of the at leastone channel of the unlicensed spectrum based at least on thetransmission cycle period, the offset parameter, and a current timervalue of a system frame number (SFN); determining, by the ED, from theconfiguration information, a channel occupancy time (COT) duration limitand a subsequent minimum idle duration applicable to each period of thesemi-static periodic access; and transmitting, by the ED, an uplink (UL)burst comprising one or more UL transmissions to initiate a channeloccupancy over the at least one channel of the unlicensed spectrum,wherein the UL burst starts at a beginning of a first period of thesemi-static periodic access immediately after determining that the atleast one channel is idle for a short deterministic duration of aone-shot clear channel assessment (CCA) procedure, and ends before astart of a minimum idle duration of the first period.
 2. The method ofclaim 1, wherein any further UL transmission or any further DLtransmission from the base station in association with the channeloccupancy initiated by the ED occurs only within the COT duration limitof the first period of the semi-static periodic access and outside theminimum idle duration of the first period.
 3. The method of claim 2,wherein the ED is pre-configured by the base station with pre-configuredtime-frequency resources for transmitting UL transmissions at one ormore transmission occasions (TOs) within the first period of thesemi-static periodic access.
 4. The method of claim 3, wherein the ULburst starts at the beginning of the first period of the semi-staticperiodic access with a first UL transmission at a first TO of the one ormore TOs, and wherein the first UL transmission is transmitted inaccordance with the pre-configured time-frequency resources, or whereina second UL transmission at a second TO of the one or more TOs is afterthe beginning of the first period of the semi-static periodic access inaccordance with the pre-configured time-frequency resources.
 5. Themethod of claim 4, wherein the second UL transmission at the second TOof the one or more TOs meets at least one of: the second UL transmissionat the second TO of the one or more TOs being transmitted within the ULburst, directly without CCA, and in association with the channeloccupancy initiated by the ED over the at least one channel of theunlicensed spectrum, the second UL transmission at the second TO of theone or more TOs being transmitted, directly without CCA, after a firstgap of no longer than 16 us from a downlink (DL) burst, wherein thesecond UL transmission ends before the start of the minimum idleduration of the first period and is in association with the channeloccupancy initiated by the ED over the at least one channel of theunlicensed spectrum, the second UL transmission at the second TO of theone or more TOs being transmitted after a second gap of more than 16 usfrom the DL burst or transmitted after the UL burst immediately afterthe ED determining that the at least one channel is idle for the shortdeterministic duration of the one-shot CCA procedure, wherein the secondUL transmission ends before the start of the minimum idle duration ofthe first period and is in association with the channel occupancyinitiated by the ED over the at least one channel of the unlicensedspectrum, or the second UL transmission at the second TO of the one ormore TOs not ending before the start of the minimum idle duration of thefirst period and is not transmitted in association with the channeloccupancy initiated by the ED over the at least one channel of theunlicensed spectrum.
 6. The method of claim 3, wherein the ED starts theUL burst with a UL transmission carrying control information over aphysical uplink control channel (PUCCH) or with a reference signal (RS).7. The method of claim 3, wherein the ED receives a first DLtransmission not in association with the channel occupancy initiated bythe ED within the minimum idle duration of the first period of thesemi-static periodic access.
 8. The method of claim 3, wherein the EDreceives a first DL transmission transmitted directly by the basestation without CCA, after a first gap of no longer than 16 us from anend of the UL burst, wherein the first DL transmission ends before thestart of the minimum idle duration of the first period and is inassociation with the channel occupancy initiated by the ED over the atleast one channel of the unlicensed spectrum, or wherein the ED receivesa second DL transmission after a second gap of at least 25 us from anend of any DL burst or any UL burst and immediately after the basestation determining that the at least one channel is idle for the shortdeterministic duration of the one-shot CCA procedure, wherein the secondDL transmission ends before the start of the minimum idle duration ofthe first period and is in association with the channel occupancyinitiated by the ED over the at least one channel of the unlicensedspectrum.
 9. The method of claim 2, wherein the ED receives a first DLtransmission in association with the channel occupancy initiated by theED over the at least one channel of the unlicensed spectrum if the firstDL transmission at least carries DL data or control information intendedfor the ED.
 10. The method of claim 9, wherein the first DL transmissionin association with the channel occupancy initiated by the ED furtherincludes other control information intended for other EDs.
 11. Themethod of claim 1, further comprising: receiving, by the ED, asemi-static periodic DL transmission over the at least one channel inthe unlicensed spectrum, wherein a period of the semi-static periodic DLtransmission is configured as an integer multiple of the transmissioncycle period.
 12. A method comprising: transmitting, by a base stationto an electronic device (ED), configuration information, theconfiguration information indicating at least a transmission cycleperiod and an offset parameter for semi-static periodic access of atleast one channel of an unlicensed spectrum, a reference start time forthe semi-static periodic access of the at least one channel of theunlicensed spectrum being based at least on the transmission cycleperiod, the offset parameter, and a current timer value of a systemframe number (SFN), a channel occupancy time (COT) duration limit and asubsequent minimum idle duration applicable to each period of thesemi-static periodic access being based at least on the transmissioncycle period; and receiving, by the base station from the ED, an uplink(UL) burst comprising one or more UL transmissions to initiate a channeloccupancy over the at least one channel of the unlicensed spectrum,wherein the UL burst starts at a beginning of a first period of thesemi-static periodic access immediately after determining that the atleast one channel is idle for a short deterministic duration of aone-shot clear channel assessment (CCA) procedure, and ends before astart of a minimum idle duration of the first period.
 13. The method ofclaim 12, wherein any further UL transmission or any further DLtransmission from the base station in association with the channeloccupancy initiated by the ED occurs only within the COT duration limitof the first period of the semi-static periodic access and outside theminimum idle duration of the first period.
 14. The method of claim 13,wherein the base station pre-configures the ED with pre-configuredtime-frequency resources for transmitting UL transmissions at one ormore transmission occasions (TOs) within the first period of thesemi-static periodic access.
 15. The method of claim 14, wherein the ULburst starts at the beginning of the first period of the semi-staticperiodic access with a first UL transmission at a first TO of the one ormore TOs, and wherein the first UL transmission is transmitted inaccordance with the pre-configured time-frequency resources, or whereina second UL transmission at a second TO of the one or more TOs is afterthe beginning of the first period of the semi-static periodic access inaccordance with the pre-configured time-frequency resources.
 16. Themethod of claim 15, wherein the second UL transmission at the second TOof the one or more TOs meets at least one of: the second UL transmissionat the second TO of the one or more TOs being transmitted within the ULburst, directly without CCA, and in association with the channeloccupancy initiated by the ED over the at least one channel of theunlicensed spectrum, the second UL transmission at the second TO of theone or more TOs being transmitted, directly without CCA, after a firstgap of no longer than 16 us from a downlink (DL) burst, wherein thesecond UL transmission ends before the start of the minimum idleduration of the first period and is in association with the channeloccupancy initiated by the ED over the at least one channel of theunlicensed spectrum, the second UL transmission at the second TO of theone or more TOs being transmitted after a second gap of more than 16 usfrom the DL burst or transmitted after the UL burst immediately afterthe ED determining that the at least one channel is idle for the shortdeterministic duration of the one-shot CCA procedure, wherein the secondUL transmission ends before the start of the minimum idle duration ofthe first period and is in association with the channel occupancyinitiated by the ED over the at least one channel of the unlicensedspectrum, or the second UL transmission at the second TO of the one ormore TOs not ending before the start of the minimum idle duration of thefirst period and is not transmitted in association with the channeloccupancy initiated by the ED over the at least one channel of theunlicensed spectrum.
 17. The method of claim 14, wherein the ED startsthe UL burst with a UL transmission carrying control information over aphysical uplink control channel (PUCCH) or with a reference signal (RS).18. The method of claim 14, wherein the base station transmits a firstDL transmission not in association with the channel occupancy initiatedby the ED within the minimum idle duration of the first period of thesemi-static periodic access.
 19. The method of claim 14, wherein thebase station transmits a first DL transmission transmitted directly bythe base station without CCA, after a first gap of no longer than 16 usfrom an end of the UL burst, wherein the first DL transmission endsbefore the start of the minimum idle duration of the first period and isin association with the channel occupancy initiated by the ED over theat least one channel of the unlicensed spectrum, or wherein the basestation transmits a second DL transmission after a second gap of atleast 25 us from an end of any DL burst or any UL burst and immediatelyafter the base station determining that the at least one channel is idlefor the short deterministic duration of the one-shot CCA procedure,wherein the second DL transmission ends before the start of the minimumidle duration of the first period and is in association with the channeloccupancy initiated by the ED over the at least one channel of theunlicensed spectrum.
 20. The method of claim 13, wherein the basestation transmits a first DL transmission in association with thechannel occupancy initiated by the ED over the at least one channel ofthe unlicensed spectrum if the first DL transmission at least carries DLdata or control information intended for the ED.
 21. The method of claim20, wherein the first DL transmission in association with the channeloccupancy initiated by the ED further includes other control informationintended for other EDs.
 22. The method of claim 12, further comprising:transmitting, by the base station to the ED, a semi-static periodic DLtransmission over the at least one channel in the unlicensed spectrum,wherein a period of the semi-static periodic DL transmission isconfigured as an integer multiple of the transmission cycle period. 23.An electronic device (ED) comprising: at least one processor; and anon-transitory computer readable storage medium storing programming, theprogramming including instructions that, when executed by the at leastone processor, cause the ED to perform operations including: receiving,from a base station, configuration information, the configurationinformation indicating at least a transmission cycle period and anoffset parameter for semi-static periodic access of at least one channelof an unlicensed spectrum; determining a reference start time for thesemi-static periodic access of the at least one channel of theunlicensed spectrum based at least on the transmission cycle period, theoffset parameter, and a current timer value of a system frame number(SFN); determining from the configuration information, a channeloccupancy time (COT) duration limit and a subsequent minimum idleduration applicable to each period of the semi-static periodic access;and transmitting an uplink (UL) burst comprising one or more ULtransmissions to initiate a channel occupancy over the at least onechannel of the unlicensed spectrum, wherein the UL burst starts at abeginning of a first period of the semi-static periodic accessimmediately after determining that the at least one channel is idle fora short deterministic duration of a one-shot clear channel assessment(CCA) procedure, and ends before a start of a minimum idle duration ofthe first period.
 24. Abase station comprising: at least one processor;and a non-transitory computer readable storage medium storingprogramming, the programming including instructions that, when executedby the at least one processor, cause the base station to performoperations including: transmitting, to an electronic device (ED),configuration information, the configuration information indicating atleast a transmission cycle period and an offset parameter forsemi-static periodic access of at least one channel of an unlicensedspectrum, a reference start time for the semi-static periodic access ofthe at least one channel of the unlicensed spectrum being based at leaston the transmission cycle period, the offset parameter, and a currenttimer value of a system frame number (SFN), a channel occupancy time(COT) duration limit and a subsequent minimum idle duration applicableto each period of the semi-static periodic access being based at leaston the transmission cycle period; and receiving, from the ED, an uplink(UL) burst comprising one or more UL transmissions to initiate a channeloccupancy over the at least one channel of the unlicensed spectrum,wherein the UL burst starts at a beginning of a first period of thesemi-static periodic access immediately after determining that the atleast one channel is idle for a short deterministic duration of aone-shot clear channel assessment (CCA) procedure, and ends before astart of a minimum idle duration of the first period.